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  • richardmitnick 8:22 am on January 29, 2021 Permalink | Reply
    Tags: "Astronomers want to plant telescopes on the Moon", Astronauts might one day assemble a large infrared telescope on the Moon., , Astronomy magazine, , , , Once astronomers pick an ideal landing site they can then figure out how to transport all the necessary equipment which needs to neatly fit in a rocket., , The Moon would shield the telescope from almost all the radio interference from Earth., The telescope would need a satellite to transmit data to scientists on Earth.   

    From Astronomy Magazine: “Astronomers want to plant telescopes on the Moon” 

    From Astronomy Magazine

    January 19, 2021
    Ramin Skibba

    The lunar surface offers advantages for infrared and radio astronomy, despite the challenges.

    1
    An artist’s conception of astronauts setting up a lunar telescope array. Credit: NASA.

    For decades, even before the iconic Hubble telescope took flight, astronomers have been launching spacecraft into orbit in the hopes of avoiding atmospheric effects that blur images taken by telescopes on Earth. But to catch clear signals of some cosmic objects, even those orbits aren’t high enough.

    A group of astronomers now make the case for assembling and planting telescopes on the Moon. In a series of newly published papers in The journal Philosophical Transactions of the Royal Society A, they argue that our lunar neighbor, especially its far side, makes an excellent place for telescopes in the radio and infrared range. These telescopes could discover and study potentially life-friendly planets outside our solar system and explore the little-understood “dark ages” of the young universe, around a million years after the Big Bang, when the first stars formed.

    “This is the time to start discussing projects on the Moon. There’s a huge international focus on returning to the Moon, and we wanted to make sure that science gets considered as a priority,” said Joseph Silk, a University of Oxford astrophysicist who authored multiple papers in the series.

    Astronomers have already built sensitive radio telescopes on Earth, like the Low-Frequency Array (LOFAR) in Europe, but they have limits.

    ASTRON LOFAR Radio Antenna Bank, Netherlands.

    The Earth’s upper atmosphere blocks radio signals shorter than 10 megahertz or so, limiting what the telescopes can see, said Jack Burns, a University of Colorado astronomer and director of the Network for Exploration and Space Science U Colorado Boulder. Furthermore, interference from radio signals people use to communicate — including cellphones, Wi-Fi and satellites — can increasingly drown out the signals from the cosmos as these technologies become more widespread. Space telescopes can provide major improvements, but even when they’re orbiting hundreds of miles away, they can’t get away from it all. “The far side of the Moon is the only place in the inner solar system that is truly radio quiet,” said Burns. “I spent two years of my Ph.D. developing techniques to get rid of [radio] interference,” said Jake Turner, a Cornell University astronomer who works with LOFAR and other telescopes on the ground. Turner and his colleagues are using radio astronomy to try to detect the radio signals that some planets with magnetic fields emit.

    Only some planets have magnetic fields, Turner said, depending on the planet’s internal structure, and their presence or absence could be a major factor determining whether life might flourish there. Many of the planets outside our solar system discovered so far closely orbit red dwarf stars, which often spew huge blobs of charged particles that could erode a planet’s protective atmosphere and harm life forms on the surface. A magnetic field would help deflect such stellar storms and protect the planet’s atmosphere from being stripped away.

    Turner has figured out how to detect the magnetic fields of relatively large planets, but those of smaller, Earth-sized worlds, which could be friendly to life, unfortunately emit radio waves too faint with frequencies too short to be seen through the noise in our atmosphere. A telescope placed on the far side of the Moon, however, would take advantage of the Moon itself, which would shield the telescope from almost all the radio interference from Earth.

    That’s the idea behind a proposed mission called FARSIDE [NASA JPL/Caltech] that Burns is leading. The plan is for a robotic lunar rover to set up an array of antennas that could scan the entire sky over a range of low radio frequencies. Its main objectives would include identifying life-friendly planets through their magnetic fields as well as monitoring energetic particles released by the host stars. If NASA proceeds with the project, construction of the telescope could begin in the late 2020s and be deployed soon afterward.

    FARSIDE would be small and uncomplicated, not like the giant half-kilometer-wide dishes astronomers have built on Earth. But Silk and his colleagues suggest that, further down the road, astronauts might one day assemble a large infrared telescope on the Moon. Infrared telescopes must be kept sufficiently cool so that their own infrared heat doesn’t interfere with their operation, and this might be accomplished by locating it in a permanently shadowed site, like in a crater near the moon’s south pole. Such a telescope could be used to spot faint planets and even keep an eye on their weather and seasons.

    When it comes to constructing such big lunar telescopes, the instruments and structures fortunately wouldn’t be affected by wind as they are on Earth, and the smaller force of gravity on the Moon would help, too, Silk said.

    Even if we can’t see the far side of the Moon from Earth, astronomers aren’t in the dark about what it looks like: NASA’s Lunar Reconnaissance Orbiter and other spacecraft periodically map out the terrain, making it possible to scope out the best spots for telescopes.

    NASA/Lunar Reconnaissance Orbiter

    Once astronomers pick an ideal landing site, they can then figure out how to transport all the necessary equipment, which needs to neatly fit in a rocket. A robot or astronauts would have to assemble the telescope, and once the instrument is up and running, it would need a satellite to transmit data to scientists on Earth.

    There are other challenges to making our lunar neighbor a home for telescopes. “The Moon has dust, so it’s a dirty environment, and you’d have to mitigate that. The Moon also has some seismic activity, mostly due to impacts from small meteors,” said Marc Postman, an astronomer at the Space Telescope Science Institute. But there are benefits to being on the Moon, he said, and if a telescope is near a lunar base, robots or astronauts could repair or upgrade it, when needed.

    Martin Elvis, a Harvard astrophysicist who wrote another paper in the series, raises yet another problem. The Moon might have the surface area of Africa, but the prime areas that are attractive to astronomers, astronauts and would be Moon-miners — like the Peaks of Eternal Light on the south pole — are rather small. While the place doesn’t have the cultural significance of Hawaii’s Mauna Kea, it could become just as crowded. “There will be disputes sooner than you think,” he said.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Astronomy is a magazine about the science and hobby of astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of the University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at the University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
  • richardmitnick 10:03 am on January 15, 2021 Permalink | Reply
    Tags: "Arecibo is dead. Should we build its replacement on the Moon?", , Astronomy magazine, , , Build a radio telescope on the far side of the Moon because the lunar far side always faces away from Earth-the entire Moon acts as a shield that blocks Earth's cacophony of outgoing radio noise., , In recent years NASA has shown support for these ideas at levels never seen before., NASA may finally be serious about the idea of building a large radio telescope in a lunar crater., , Saptarshi Bandyopadhyay a robotics technologist at the Jet Propulsion Laboratory and leader on the Lunar Crater Radio Telescope project team says build LCRT using simple lunar rovers already designed.   

    From Astronomy Magazine: “Arecibo is dead. Should we build its replacement on the Moon?” 

    From Astronomy Magazine

    January 6, 2021
    Eric Betz

    NASA may finally be serious about the idea of building a large radio telescope in a lunar crater.

    When the 60-year-old Arecibo Observatory collapsed in 2020, the crash didn’t just take down one of the world’s preeminent radio telescopes, it also dealt a massive blow to the future of radio astronomy. Arecibo may have been old, but it also had unique capabilities that made it ideal for studying things like gravitational waves, as well as mapping the surfaces of asteroids as they slip by Earth.

    NAIC Arecibo Observatory operated by University of Central Florida, Yang Enterprises and UMET, Altitude 497 m (1,631 ft), which has now collapsed.

    1
    Since the 1960s, astronomers have dreamed about building radio telescopes on the farside of the Moon, which would shield them from Earth-based interference. Credit:NASA.

    Now, radio astronomers around the world are debating what comes next. Should Arecibo be rebuilt anew? If so, where would the money come from?

    Those questions don’t have easy answers, but the discussions are happening. Preliminary plans for another revolutionary radio telescope continue to inch forward every day. And interestingly, these talks have led NASA to reconsider a bold idea that was first dreamed up a half-century ago: building a behemoth radio telescope on the farside of the Moon.

    Arecibo’s design benefited from being built in a natural sinkhole in Puerto Rico. Similarly, astronomers could use existing lunar craters to build a radio telescope on the Moon for (relatively) cheap; impacting space rocks have already done the digging for them. And unlike Earth, the Moon has no weather or wind to accelerate erosion. Even the pull of gravity itself is weaker on the lunar surface.

    2
    A decades-old idea from lunar scientist Richard Vondrak, who worked at the Apollo Science Operations Center during the moon landing program, proposed using lunar craters to build radio telescopes like the Arecibo Observatory in Puerto Rico. Here, an artist’s concept shows how three telescopes could be used separately or combined to create a giant instrument. Credit: NASA.

    Arecibo on the Moon

    As early as the 1960s, astronomers wanted to build a radio telescope on the farside of the Moon. That’s because the lunar farside always faces away from Earth, which means the entire Moon acts as a sort of shield that blocks Earth’s cacophony of outgoing radio noise. This creates an environment where scientists could theoretically observe the universe in wavelengths that can’t be easily analyzed from our planet — or even in orbit.

    An Arecibo on the Moon would be more than a replacement, though. The premise is similar to the way astronomers decided to replace the Hubble Space Telescope. Rather than replicating the original, the community embraced the idea of building something entirely different. The James Webb Space Telescope (JWST) used insights gleaned from Hubble’s tenure, sure. But JWST was specially built to study the universe primarily through infrared light, while Hubble focuses on visible and ultraviolet light. That spectral shift means JWST will be able to investigate previously unexplored aspects of the universe with impeccable detail.

    NASA James Webb Space Telescope annotated.

    The same is true of building a large radio telescope on the Moon. While Arecibo dedicated a half-dozen decades to studying radio waves at the centimeter- and millimeter-scale, a lunar radio telescope could monitor wavelengths larger than a meter, something astronomers can’t do from Earth.

    If an Arecibo-like observatory was built on the Moon, it could potentially spot many exotic cosmic phenomena, such as auroras around distant Earth-like exoplanets. Most alluringly, it could even pick up radio signals from the earliest days of the cosmos, before the first stars and galaxies were born.

    3
    A 1986 proposal suggested a system of cables suspended inside a lunar crater could let astronomers construct an Arecibo-style telescope on the Moon. Credit: NASA.

    Frank Drake, a world-renowned astronomy, even once pitched the idea for “Very Large Arecibo-Type Telescopes” on the Moon at a NASA conference in 1986. Drake reasoned that utilizing a lunar crater would minimize the need to build large structural elements. Some panels, platforms, and a slew of cables might suffice, he suggested.

    The Moon also holds so many craters that it should be relatively easy to find one with a sturdy enough rim that it can serve as the anchor point for the telescope’s support cables. This would avoid the cost of the expensive towers that anchored cables at Arecibo. (In fact, the telescope collapsed in 2020 after the cables attached to its towers failed.)

    “Reasonable valley and crater cross sections fulfill this need quite nicely,” Drake wrote. “In this case, a substantial saving in cost and materials accrues. This approach could be used to build Arecibo-style telescopes on the Moon or on the Earth at substantial savings over the cost of the actual Arecibo design.”

    4
    An artists’ concept of how robots would build the Lunar Crater Radio Telescope. Credit: Saptarshi Bandyopadhya.

    In recent years, NASA has shown support for these ideas at levels never seen before. The space agency has even funded studies on several early proposals to finally build an Arecibo-like observatory on the Moon. Of these proposals, the Lunar Crater Radio Telescope (LCRT) echoes some of the same ideas Drake brought up a generation ago.

    But unlike previous mission designers imagined, the latest iterations of Moon-based telescopes wouldn’t rely on astronauts to construct them. Saptarshi Bandyopadhyay, a robotics technologist at the Jet Propulsion Laboratory and leader on the LCRT project team — says they intend to build LCRT using simple lunar rovers like the ones NASA has already designed.

    LCRT would land a spacecraft full of rovers outside the crater. These would then retrieve the support wires, take them to the crater rim, and assemble a mesh system spanning approximately 0.6 miles (1 kilometer). However, the whole system would have to fit inside a single lunar-landing spacecraft, like Blue Origin’s Blue Moon.

    By depending on robots instead of astronauts, the project can save a significant amount of money. Any mission involving astronauts requires extensive — and expensive — safety precautions. Every potential problem requires extra scrutiny and engineered safeguards. For example, sharp edges can slice through spacesuits, so they’re avoided on crewed flights. But rounded edges don’t allow you to maximize cargo space, which you’d want to do for a robotic trip to the Moon.

    NASA has also already begun testing a versatile model of a rover called DuAxel, which could be used for a number of different lunar missions. Among other things, DuAxel can climb crater walls. And as a bonus, it’s relatively cheap.

    “If we send 10 of these robots and two of them die; it’s fine,” Bandyopadhyay says. “Two of them are dead, but eight robots are still working. It’s not like that with astronauts.”

    6
    A rover operates inside a lunar crater in this artist’s concept. Credit: NASA.

    However, even with all the potential advantages of robotic builders, the current cost of the technology likely puts the mission out of reach. SAPART estimates that building a radio telescope on the Moon would cost billions of dollars. That’s why his team is trying to develop new kinds of cables and mesh that would be dramatical cheaper to use than what’s available now. LCRT’s initial study relied on $120,000 of NASA Innovative Advanced Concepts (NIAC) project funding to investigate the concept. And the next stage of their mission plan would let engineers get to work on developing the mesh. By spring, Bandyopadhyay says, his team hopes to publish their initial results.

    “We have a good first design now that makes sense and that we could potentially fly,” he says. “If you gave us four or five billion dollars we could launch it tomorrow.”

    But despite the enthusiasm, Bandyopadhyay isn’t optimistic we’ll see an Arecibo-style telescope on the Moon in the near future. After all, science tends to be slow.

    “I would be very surprised if I see LCRT deployed before I retire, and I’m a very young scientist,” Bandyopadhyay says. “These things are hard. These questions we are trying to solve are hard. And the science windows these questions will open are hard. Everything is hard. If it was easy, we would have done it already.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Astronomy is a magazine about the science and hobby of astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of the University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at the University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
  • richardmitnick 8:52 am on January 13, 2021 Permalink | Reply
    Tags: "The lonely universe- Is life on Earth just a lucky fluke?", Abiogenesis, , Astronomy magazine, , , , ,   

    From Astronomy Magazine: “The lonely universe- Is life on Earth just a lucky fluke?” 

    From Astronomy Magazine

    November 16, 2020 [Missed this one.]
    Sarah Scoles

    Life beyond might not exist — or we just don’t know how to find it.

    1
    This artist’s concept shows exoplanet Kepler-1649c orbiting around its host red dwarf star. The exoplanet is in its star’s habitable zone — the distance where liquid water could exist on the planet’s surface. After searching for signs of alien life for nearly 60 years, some astronomers wonder whether it’s really out there. Credit: NASA/Ames Research Center/Daniel Rutter.

    When physicist and author Stephen Webb was a kid in the 1960s, humans were finally reaching beyond Earth. Satellites orbited the planet. Rockets blasted people into space. Astronauts walked on the moon. And in the distance, Mars, with its red soil and hints of ancient water, titillated imaginations and beckoned Earthlings onward.

    “I grew up — I guess you’d say — in a science fictional world,” says Webb, a bald British man whose alternately arched and furrowed eyebrows can tell a story of excitement and confusion almost as well as words do.

    During that same childhood period, he was immersing himself in actual science fiction, in addition to this nonfictional reality that was so cool it seemed fake. He devoured books by canonical authors like Robert Heinlein and Isaac Asimov. In the universe-webs the writers spun, humans rocketed around and interacted with interplanetary species. That lens shaped his view of everything — and everyone — in space. He came of age, he says, with “that idea that the galaxy contains weird and wonderful life-forms that one day we would go out and meet.”

    Webb held on to that idea tightly — until, that is, as a young man studying physics, he read an August 1984 article in the magazine Asimov’s Science Fiction, written by geologist and science fiction author Stephen L. Gillett. It was called simply The Fermi Paradox, and it proposed something Webb had never considered: If the universe is so big, it likely produced intelligent life on other planets. Some of those lives must have built spaceships. Even at relatively slow speeds, given enough time, they’d disperse across the galaxy, just as humans had across the globe. And if that’s the case, as physicist Enrico Fermi famously wondered, where is everybody? Why haven’t we met any extraterrestrials?

    “It just hit me with the force of a sledgehammer that all these things that science fiction, and science as well, had told me to expect — that one day soon we would make contact with aliens, and that maybe we’d go out and have all these Star Trek adventures with them — maybe that was all wrong,” says Webb.

    Just as Asimov had given, Asimov had taken away, and Webb found himself in a new and unfamiliar universe. The assault to his preconceptions needled him, but he liked challenges, and he took this one on. “I got into the habit of starting to collect solutions to the so-called Fermi paradox,” he says. In notebooks and desk drawers and, eventually, computer files, he amassed a set of explanations for where “everybody” might be. The pile of potentials became a book in 2002: If the Universe Is Teeming With Aliens … Where Is Everybody? 75 Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life. In it, Webb argues with himself, vacillating between his childhood vision of a populated universe and that metaphorical sledgehammer. Maybe SETI scientists have not found any extraterrestrials because none exist.

    Other scientists hold up the possibility that extraterrestrial smarts don’t resemble ours, or that scientists are so stuck on Earth’s current technology that they’re blinded to more exotic possibilities. Perhaps if those same researchers set their agendas right, the coming 60 years will help earthlings figure out which hypothesis — and which vision of the cosmos — is correct.

    The modernity problem

    “If you go outside and look up on a clear night, it’s almost impossible to believe that we are alone,” says Webb. In England, he doesn’t get many clear nights. But when he does, and he steps outside and sets his gaze skyward, he sees the same constellations dot-to-dotting that he did in the Apollo era. He still feels the pull of his childhood ideas. “There’s something innate in this feeling that we cannot be alone,” he says.

    And that’s part of why he started collecting the Fermi solutions and setting them down in sentences. With a doctorate in theoretical particle physics from the University of Manchester, he was equipped to find, review, and evaluate the many ideas in his scientific realm. Having published eight science books with academic presses and having been invited to give a 2018 TED talk about his research, Webb is a well-recognized figure in the landscape of SETI. “I didn’t enter [the book] with a particular ax to grind,” he says. “And, in fact, I think I wrote it to kind of explore this in my own mind.” Webb’s book — and the pile of papers before that — explores dozens of Fermi solutions, under section headers like They Are (or Were) Here and They Exist, but We Have Yet to See or Hear From Them.

    Many of Webb’s collected hypotheses suggest that aliens live where we’re not looking, talk how we’re not listening or resemble something we haven’t sought out. Maybe the aliens like to send messages or signals using neutrinos, nearly massless and barely-there particles that don’t interact with normal matter much, or tachyons, hypothetical particles that fly faster than light. Maybe they use the more-conventional radio or optical transmissions but at frequencies, or in a form, astronomers haven’t sought out. Maybe a signal is sitting on data servers already, escaping notice. Maybe the extraterrestrials subtly alter the emissions of their stable stars, or the blip-blip-blip pulsations of variable stars. Maybe they put something big — a megamall, a disk of dust — in front of their sun to block some of its light, in a kind of anti-beacon. Maybe their skies are cloudy, and they consequently don’t care about astronomy or space exploration. Or — hear Webb out — perhaps they drive UFOs, meaning they are here but not in a form that scientists typically recognize, investigate, and take seriously.
    In 2015, Webb published a second edition of the book, because in the intervening years, others had postulated even more ways of seeing a signal. His favorites involve phenomena astronomers have studied closely only in the past decade or so. Maybe aliens could “spin up” millisecond pulsars — dead stars as dense as atomic nuclei that spin hundreds of times per second — giving them an energy bump like Hot Wheels cars passing over booster tracks. Or perhaps the cosmic cousins prefer to communicate using gravitational waves, the ripples in spacetime that earthlings just learned how to detect in 2015.

    3
    The discovery of Kepler-186f, shown in this artist’s concept, confirmed that Earth-size planets exist in the habitable zones of other stars, and signaled a significant step closer to finding a world similar to Earth. Credit: NASA/Ames/SETI Institute/JPL-Caltech.

    There’s a problem with these ideas, though: They suffer from a modernity bias, a term historians and political scholars sometimes use. It means that we tend to conceive of society’s current state as both inevitable and significant — the most significant — and view all else through this lens. “We tend to look at, to think about, what civilizations might do in terms of our understanding of technology,” Webb says. We imagine, at any given time, that aliens might have discovered technology similar to whatever our latest-greatest innovations are. In the 19th century, canals transformed terrestrial cities. And astronomer Percival Lowell popularized the idea that little green people had constructed canals on Mars. After humans mastered radio communication, astronomers suddenly thought the aliens might, too. Ditto, lasers. Ditto, gravitational waves.

    The aliens, should they exist, might be using technology humans won’t invent for millennia, if at all. And while scientists do sometimes see past Earth’s technological thresholds, they (and the rest of us) are notoriously bad at imagining where our own technology is going (did anyone predict Uber would come out of ARPANET?). How, then, could it be possible to imagine where alien technology might go?

    Anthropologist Michael Oman-Reagan, who studies SETI scientists’ culture at Memorial University in Newfoundland, thinks modernity bias might be keeping scientists from seeing an alien fingerprint right in front of them. “It might look like nature or magic, or any number of things,” he says. “It might look like the background processes of the universe. It might look like physics.”

    Maybe we’re alone

    Webb thinks that maybe there is no right thing. It’s an idea he lays out in the book’s most interesting section, with the scariest subtitle: They Don’t Exist. There is no “everybody.” “It is just us,” he says, almost trying the idea on. The notion, he says, can feel as cold as the universe itself.

    As he gathered his 75 solutions, Webb kept flipping between that intuitive emotion and what he realized his forebrain truly thought. “We’re just a rare fluke,” he says, sounding resigned.

    Astronomers often suggest that’s unlikely. There are so many exoplanets, possibly multiple trillions just in our galaxy, and there are 2 million to 8 million (depending on which biologist you ask) species on Earth inhabiting even the most hostile places — from the cooling tanks of nuclear reactors to super-salty lakes to the crushing depths of the way-down ocean. Given the size of the universe and the sprawl of potentially habitable real estate, sheer statistics mean life has to exist. At least, that’s the traditional line of thinking. “Ultimately, the argument they are putting forth is that there are, for the sake of argument, a trillion places that life could get going on, and that’s a big number,” Webb says.

    There’s a problem with that logic, though: “We don’t know in this context whether a trillion is a big number or not,” he says. That depends on statistical calculations.

    Here’s how the statistical calculations work: To get intelligent life, you need solar systems with home stars that aren’t too violent. Those systems have to have habitable planets. Those planets have to go from empty to alive somehow, in a process called abiogenesis. Once life arises, it has to stay alive. Then, it not only has to evolve into something smart, but the smart things also have to develop technology. No one knows how likely any of those things is. Each if-then represents a kind of turning point, a transition from one phase to another. “They don’t need to be hugely rare transitions, if there are many of them, for ‘a trillion’ to actually appear quite small,” says Webb.

    Many biologists, for instance, think abiogenesis is much more difficult than many astronomers think, and no one knows how it happened on Earth. While some scientists suspect that life inevitably progresses toward complication and intelligence, that’s a human-centric bias. “We don’t know if intelligence is a winning evolutionary strategy,” Webb points out. After all, some of the oldest species on Earth, including cyanobacteria (3.5 million years old), coelacanths (65 million years old) and crocodiles (55 million years old), are not smart by human standards. They definitely wouldn’t be able build a radio telescope or wonder if they were alone in the universe. Nevertheless, they persist, arguably better than we have.

    Oman-Reagan’s research examines these kinds of assumptions, the ones scientists often bring without even realizing it. The conception of humans as the most intelligent and capable species on Earth? That might just be our ego talking. “The most advanced species on Earth might be the one that does the least harm, not the most,” he says. To that end, he believes SETI would do well to abandon the idea that technological civilizations are superior, the progressive and predictable result of evolution. While the scientists themselves might not necessarily put their thought process that way, the underlying idea is nevertheless that advanced technology will result from long-term evolution. These scientists recognize that not all “smart” beings may use technology like humans do, but the belief remains that life trends toward increasingly complex tool-use.

    That’s part of the traditional definition of cultural evolution, a social-science term. But it’s “not clear at all” that when a civilization continues existing for a long time, it inevitably becomes ever more technological, says University of Texas anthropologist John Traphagan, who studies the relationship between culture, religion and science in SETI. There’s not necessarily a reason, then, to think that old aliens would be engineering wormholes or spooling up beacon-broadcasters.

    Similarly, Traphagan takes issue with another SETI argument: The longer a technological civilization persists, the more likely it is to be nice, because it’s learned how to resolve conflict without apocalypse. “There’s no reason to think that altruism is going to be an outgrowth of technological superiority,” says Traphagan. “Predators are usually the ones that have the highest intelligence.” Besides, why would a planetary society be monolithic in any way — good or bad? Humans certainly are not. Astronomers’ ideas on this point don’t make sense to him.

    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA, Altitude 986 m (3,235 ft), the origins of the Institute’s search.



    Given these quibbles, he’s frustrated that astronomers often discuss the psychology of the cosmic “everybody.” “Why is it that an astronomer who has no training in social science and culture can write extensively about the nature of these things as they apply to an imaginary civilization in space?” he says. “To me it makes no sense. Just being smart isn’t enough.”

    If social scientists were in charge of the search, he says, it might progress in a different direction. Such scientists do get invited to SETI workshops and conferences, and to contribute chapters to scholarly books about the search. But these religion researchers, historians, anthropologists and communications experts occupy the fringes of the field.

    Webb thinks that may not matter. Chances are, he believes, there are no civilizations to contact, and so perhaps our efforts to undo assumptions, confront biases, and expand our intellectual horizons don’t affect the end result: silence, emptiness.

    Researchers at the University of Oxford’s Future of Humanity Institute recently quantified that feeling. To calculate how many intelligent, communicative civilizations may be in our galaxy, scientists usually use the so-called Drake equation.

    Drake Equation, Frank Drake, Seti Institute.


    Frank Drake with his Drake Equation. Credit Frank Drake.

    It’s a way of mathifying the evolutionary progression of a civilization from nothingness to life, first introduced in 1961 by astrophysicist Frank Drake, with each transition representing a term in an equation. The problem with these terms, though, is that we don’t know what number to assign them: The possibilities have a range of uncertainties.

    Computational neuroscientist Anders Sandberg and his colleagues at the institute wanted to include all of that doubt in their own Drake calculations, to shed some light on the dark, quiet universe. “It seemed to me that there is important information in the empty sky,” says Sandberg. Instead of assigning actual numbers to each term in the equation, they used the full range of numbers, for each term, that reasonable research suggests.

    The probability distributions that resulted surprised even them: Humans, they found, are likely to be alone in the observable universe, a possibility between 39 and 85 percent. “It’s actually a fairly plausible thing,” says Sandberg. The team calculated that in the Milky Way galaxy, there’s between a 53 and 99.6 percent chance we’re alone.

    That is, of course, just one group’s estimate. And “alone” doesn’t necessarily mean that there never was anybody. Maybe they were and just are not anymore, because of nuclear holocaust, irreversible climate change, epidemics run amok, asteroid impacts, nearby gamma-ray bursts, apocalypses we can’t imagine. Or maybe they never existed in the first place. Sandberg spins this possibility positively. If civilizations never existed, then the sky isn’t silent because they all destroyed themselves. “An empty sky doesn’t mean we are doomed,” says Sandberg.

    Webb maintains a similar mindset. “I do have that basic optimism, which probably comes from science fiction,” he says, “that we will persist over centuries and millennia.” Perhaps even long enough to find out through SETI — which all of these naysayers actually believe we should continue — whether “everybody” includes anybody but us.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Astronomy is a magazine about the science and hobby of astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of the University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at the University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
  • richardmitnick 6:32 pm on January 10, 2021 Permalink | Reply
    Tags: "This huge galaxy has the biggest black hole ever measured", , Astronomy magazine, , , , Quasars-galaxies with massive central black holes that emit huge amounts of light as they gobble up nearby matter in a process called accretion.   

    From Astronomy Magazine: “This huge galaxy has the biggest black hole ever measured” 

    From Astronomy Magazine

    December 5, 2019 [Just found this in social media]
    Erika K. Carlson

    The monster black hole in galaxy cluster Abell 85 is roughly the size of our solar system, but packs the mass of 40 billion suns.

    1
    The Abell 85 galaxy cluster, shown here, is home to the largest black hole known in the universe. Credit: Matthias Kluge/USM/MPE.

    Astronomers have found the biggest black hole ever measured — it’s 40 billion times the sun’s mass, or roughly two-thirds the mass of all stars in the Milky Way. The gargantuan black hole lurks in a galaxy that’s supermassive itself and probably formed from the collisions of at least eight smaller galaxies.

    Holm 15A is a huge elliptical galaxy at the center of a cluster of galaxies called Abell 85. A team of astronomers captured a snapshot of Holm 15A’s stars in orbit around the galaxy’s central black hole and created a model to help them calculate the black hole’s mass. The team described their findings in a recent paper published in The Astrophysical Journal.

    Making monster galaxies

    When two spiral galaxies — like our Milky Way and the nearby Andromeda Galaxy — collide, they can merge and form an elliptical galaxy.

    Milkdromeda with Andromeda on the left-Earth’s night sky in 3.75 billion years. No one will be here on Earth to see it. Maybe humans will have escaped the Sun’s becoming a Red Giant and observe it from a new home. Credit: NASA.

    Milky Way merger with Andromeda. Credit: NAOJ .

    In crowded environments like galaxy clusters, these elliptical galaxies can collide and merge again to form an even larger elliptical galaxy. Their central black holes combine as well and make larger black holes, which can kick huge swaths of nearby stars out to the edges of the newly formed galaxy.

    The resulting extra-large elliptical galaxy usually doesn’t have much gas from which to form new stars, so its center looks pretty bare after its black hole kicks out nearby stars. Astronomers call these huge elliptical galaxies with faint centers “cored galaxies.” Massive cored galaxies often sit in the centers of galaxy clusters.

    The authors of the new study found that Holm 15A, the enormous galaxy at the center of its home galaxy cluster, must have formed from yet another merger of two already-huge cored elliptical galaxies. That would mean Holm 15A probably formed from the combination of eight smaller spiral galaxies over billions of years. Pairs of spiral galaxies form elliptical galaxies, pairs of those ellipticals form cored elliptical galaxies, and a pair of cored galaxies formed Holm 15A. This series of mergers also created the black hole in its center, a monster about as big as our solar system but with the mass of 40 billion suns.

    Explaining quasars

    The researchers are excited to find the most massive black hole ever measured.

    “Just imagining a black hole that is so huge is cool,” said Jens Thomas, an astronomer at the Max Planck Institute for Extraterrestrial Physics in Germany and one of the study’s authors.

    But the finding is also exciting because it lends support to astronomers’ current understanding of quasars, distant galaxies with massive central black holes that emit huge amounts of light as they gobble up nearby matter in a process called accretion. Studying quasars made astronomers think that black holes 10 billion or more solar masses must exist for some of these faraway quasars to be so bright.

    “Finally, we managed to find one nearby, which sort of confirms that our idea of how quasars work and how the accretion on black holes can explain them makes sense,” said study author Roberto Saglia, also of the Max Planck Institute.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Astronomy is a magazine about the science and hobby of astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of the University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at the University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
  • richardmitnick 11:57 am on January 8, 2021 Permalink | Reply
    Tags: "What would Earth look like to alien astronomers?", , Astronomy magazine, , , ,   

    From Astronomy Magazine: “What would Earth look like to alien astronomers?” 

    From Astronomy Magazine

    December 28, 2020 [Just now in social media.]
    Nathaniel Scharping

    A new paper asks which exoplanets could find Earth. Such worlds could be targets for SETI searches.

    1
    This artist’s concept depicts Kepler-186f, a potentially habitable planet discovered by NASA’s Kepler Space Telescope.
    Credit: NASA Ames/SETI Institute/JPL-Caltech.

    Ever since 1992, when astronomers first discovered two rocky planets orbiting a pulsar in the constellation Virgo, humans have known that other worlds exist beyond our solar system. Today, thanks to the efforts of astronomers and ambitious missions like the now-retired Kepler, we know of more than 4,000 confirmed exoplanets.

    NASA/Kepler Telescope, and K2 March 7, 2009 until November 15, 2018.

    But if we can see exoplanets orbiting distant stars, that means extraterrestrial observers should be able to see Earth orbiting the Sun. Our tiny blue marble even could be on an alien astronomer’s list of rocky exoplanets capable of harboring life.

    That’s a speculative scenario, of course, but it’s one astronomers still take seriously. In multiple papers over the years, they’ve identified which exoplanets would be able to spot Earth. And now, with updated information from the European Space Agency’s expansive Gaia catalog of nearby stars, two researchers have provided us with perhaps the best list yet of which alien worlds could have their eyes on us.

    ESA (EU)/GAIA satellite .

    Observing Earth from afar

    It began with a few simple questions, says Joshua Pepper, an astronomer at Lehigh University and coauthor of the recent paper, published in October in MNRAS.

    “What if there were intelligent beings on another planet? And if they were looking at the Earth, which of those star systems could they be living in that would enable them to see Earth?” he says.

    Using data from Gaia and NASA’s Transiting Exoplanet Survey Satellite (TESS), Pepper and Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell University, went looking for planets that were aligned with Earth’s orbit around the Sun.

    NASA/MIT TESS replaced Kepler in search for exoplanets.

    This would let any alien observers witness the Sun drop in brightness a tiny bit whenever Earth passes in front of it. They cut off their search at around 330 light-years, and excluded some stars with poor data, ending up with a list of around 1,000 stars properly aligned with Earth’s orbit.

    Watching a planet pass in front of its star, known as a transit, is currently the best way we have of looking for exoplanets, Pepper says. That made it a natural choice for how other planets might spot us.

    2
    Space telescopes like NASA’s Kepler and TESS search for exoplanets using the transit method, detecting the telltale dips in brightness of a star when a planet crosses its disk. Credit: NASA Ames.

    So far, the researchers say they’ve identified five exoplanets that are near enough to Earth that extrasolar astronomers could theoretically see us. From those worlds, Earth would appear as a tiny blob of shadow passing in front of our Sun.

    And although five exoplanets is just a tiny fraction of all the worlds out there, Pepper says their list might be a good starting point for researchers involved with the Search for Extraterrestrial Intelligence, or SETI.

    “This could be a target list for SETI searches,” he says. “Any aliens on those planets would be uniquely positioned to know about the Earth.”

    Earth the Exoplanet

    From many light-years away, Earth wouldn’t look all that impressive (barring some sort of futuristic telescope technology, of course). Anyone watching Earth as a transiting exoplanet wouldn’t see our world as a verdant oasis suffused with blue, green, and tan, as we do in up-close satellite images. They’d simply see a lump of rock getting in the way of the Sun.

    But astronomers still glean plenty of information by watching exactly how a planet dims its star. They can estimate how big the world is; how quickly it orbits its star; and even the planet’s density, which tells them if it’s a gas giant like Jupiter or a rocky planet like Earth. For example, we already know this information about the five planets that Pepper and Kaltenegger think might be able to see us — they’re estimated to be super-Earths, larger than our planet but smaller than Uranus and Neptune.

    As a planet passes in front of its star, astronomers also have a rare opportunity to peer into its atmosphere (if it has one). When a thin sliver of starlight passes through the world’s gaseous envelope, it picks up information about what the atmosphere is made of.

    “When it emerges, that light is imprinted with the molecular signature of the gases that were in the atmosphere,” Pepper says. Using this information, astronomers are able to piece together the composition of exoplanet atmospheres. And while that’s a difficult task, the tactic offers astronomers one of the best ways of looking for life in the universe. That’s because the presence of oxygen, or other molecules unlikely to exist without biological life, would be a good sign of extraterrestrials on another world.

    Earth, for example, would look pretty interesting to an alien astronomer parsing the detailed contents of our atmosphere. Relatively high levels of oxygen, methane, carbon dioxide, and other gases could serve as a strong hint that our planet teems with life.

    “As far as we know, [an] atmosphere like the Earth [has], there’s really no way to mimic that without life,” Pepper says.

    An even stronger sign of extraterrestrial life could come from electromagnetic signals, like the radio waves that emanate from our telecommunications equipment. Those signals are what SETI is currently looking for elsewhere in the universe.

    Those efforts have yielded a couple of candidate signals over the years — though nothing approaching convincing evidence. For example, earlier this month, press reports surfaced of an intriguing signal discovered by the Breakthrough Listen project, appearing to originate from the star Proxima Centauri.

    Breakthrough Listen Project

    1

    UC Observatories Lick Autmated Planet Finder, fully robotic 2.4-meter optical telescope at Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California, USA




    GBO radio telescope, Green Bank, West Virginia, USA


    CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia


    SKA SARAO Meerkat telescope, 90 km outside the small Northern Cape town of Carnarvon, SA.


    Newly added

    CfA/VERITAS, a major ground-based gamma-ray observatory with an array of four Čerenkov Telescopes for gamma-ray astronomy in the GeV – TeV energy range. Located at Fred Lawrence Whipple Observatory,Mount Hopkins, Arizona, US in AZ, USA, Altitude 2,606 m (8,550 ft)

    However, the researchers have carefully noted that although they can’t explain the source of the signal yet, the most likely source is humanmade interference.

    However, if extraterrestrials were to train an equivalent to the Green Bank Observatory on Earth, they’d see a planet abuzz with electromagnetic activity. It would be a fairly slam-dunk sign that our planet holds far more than mere rocks and water.

    Another planet wouldn’t need to see Earth pass in front of the Sun to pick up our electromagnetic radiation. But Pepper says their work focuses on those planets that are most likely to find Earth. And seeing us silhouetted in front of our star is one of the best ways to do that.

    Whether we want another planet to find us, of course, is another question entirely.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Astronomy is a magazine about the science and hobby of astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of the University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at the University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
  • richardmitnick 10:16 am on January 6, 2021 Permalink | Reply
    Tags: , Astronomy magazine, , , , ,   

    From Astronomy Magazine: “Venus was once more Earth-like, but climate change made it uninhabitable” 

    From Astronomy Magazine

    January 5, 2021
    Richard Ernst

    A severe climate change event on Venus may have transformed an Earth-like climate to the current uninhabitable-to-humans state.

    1
    An artist’s rendering of the surface of Venus. Credit: Shutterstock.

    We can learn a lot about climate change from Venus, our sister planet. Venus currently has a surface temperature of 450℃ (the temperature of an oven’s self-cleaning cycle) and an atmosphere dominated by carbon dioxide (96 per cent) with a density 90 times that of Earth’s.

    Venus is a very strange place, totally uninhabitable, except perhaps in the clouds some 60 kilometres up where the recent discovery of phosphine [Nature Astronomy] may suggest floating microbial life. But the surface is totally inhospitable.

    However, Venus once likely had an Earth-like climate. According to recent climate modelling, for much of its history Venus had surface temperatures similar to present day Earth [Geophysical Research Letters]. It likely also had oceans, rain, perhaps snow, maybe continents and plate tectonics, and even more speculatively, perhaps even surface life.

    Less than one billion years ago, the climate dramatically changed due to a runaway greenhouse effect. It can be speculated that an intensive period of volcanism pumped enough carbon dioxide into the atmosphere to cause this great climate change event that evaporated the oceans and caused the end of the water cycle [JGR Planets].

    Evidence of change

    This hypothesis from the climate modellers inspired Sara Khawja, a master’s student in my group (co-supervised with geoscientist Claire Samson), to look for evidence in Venusian rocks for this proposed climatic change event [Nature Communications].

    Since the early 1990s, my Carleton University research team — and more recently my Siberian team at Tomsk State University — have been mapping and interpreting the geological and tectonic history of Earth’s remarkable sister planet.

    Soviet Venera and Vega missions of the 1970s and 1980s did land on Venus and take pictures and evaluated the composition of the rocks, before the landers failed due to the high temperature and pressure [Planetary Space Science]. However, our most comprehensive view of the surface of Venus has been provided by NASA’s Magellan spacecraft [GSFC] in the early 1990s, which used radar to see through the dense cloud layer and produce detailed images of more than 98 per cent of Venus’s surface.


    Magellan: Venus False-Color Terrain

    Ancient rocks

    Our search for geological evidence of the great climate change event led us to focus on the oldest type of rocks on Venus, called tesserae, which have a complex appearance suggestive of a long, complicated geological history. We thought that these oldest rocks had the best chance of preserving evidence of water erosion, which is a such an important process on Earth and should have occurred on Venus prior to the great climate change event.

    Given poor resolution altitude data, we used an indirect technique to try to recognize ancient river valleys. We demonstrated that younger lava flows from the surrounding volcanic plains had filled valleys in the margins of tesserae.

    To our astonishment these tesserae valley patterns were very similar to river flow patterns on Earth, leading to our suggestion that these tesserae valleys were formed by river erosion during a time with Earth-like climatic conditions [Nature Communications]. My Venus research groups at Carleton and Tomsk State universities are studying the post-tesserae lava flows for any geological evidence of the transition to extremely hot conditions.

    3
    A portion of Alpha Regio, a topographic upland on the surface of Venus, was the first feature on Venus to be identified from Earth-based radar. Credit: NASA/JPL.

    Earth analogies

    In order to understand how volcanism on Venus could produce such a change in climate, we can look to Earth history for analogues. We can find analogies in super-eruptions like the last eruption at Yellowstone that occurred 630,000 years [Geology].

    But such volcanism is small compared to large igneous provinces (LIPs) that occur approximately every 20-30 million years. These eruption events can release enough carbon dioxide to cause catastrophic climate change on Earth [Palaeogeography, Palaeoclimatology, Palaeoecology], including mass extinctions. To give you a sense of scale, consider that the smallest LIPs produce enough magma to cover all of Canada to a depth of about 10 metres [Wiley]. The largest known LIP produced enough magma that would have covered an area the size of Canada to a depth of nearly eight kilometres.

    The LIP analogues on Venus include individual volcanoes that are up to 500 kilometres across, extensive lava channels that reach up to 7,000 kilometres long, and there are also associated rift systems — where the crust is pulling apart — up to 10,000 kilometres long.

    If LIP-style volcanism was the cause of the great climate change event on Venus, then could similar climate change happen on Earth? We can imagine a scenario many millions of years in the future when multiple LIPs randomly occurring at the same time could cause Earth to have such runaway climate change leading to conditions like present-day Venus.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Astronomy is a magazine about the science and hobby of astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of the University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at the University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
  • richardmitnick 11:47 am on January 1, 2021 Permalink | Reply
    Tags: "Wandering stars pass through our solar system surprisingly often", , Astronomy magazine, , , , Scholz’s Star   

    From Astronomy Magazine: “Wandering stars pass through our solar system surprisingly often” 

    From Astronomy Magazine

    May 21, 2020 [From year end wrap up for 2020]
    Eric Betz

    Our sun has had close encounters with other stars in the past, and it’s due for a dangerously close one in the not-so-distant future.

    1
    Scholz’s Star and its binary brown dwarf fly by our solar system some 70,000 years ago in this artist’s illustration. Our sun shines bright in the background. Credit: Michael Osadciw/University of Rochester.

    Every 50,000 years or so, a nomadic star passes near our solar system. Most brush by without incident. But, every once in a while, one comes so close that it gains a prominent place in Earth’s night sky, as well as knocks distant comets loose from their orbits.

    The most famous of these stellar interlopers is called Scholz’s Star. This small binary star system was discovered in 2013. Its orbital path indicated that, about 70,000 years ago, it passed through the Oort Cloud, the extended sphere of icy bodies that surrounds the fringes of our solar system. Some astronomers even think Scholz’s Star could have sent some of these objects tumbling into the inner solar system when it passed.

    However, Scholz’s Star is relatively small and rapidly moving, which should have minimized its effect on the solar system. But in recent years, scientists have been finding that these kinds of encounters happen far more often than once expected. Scholz’s Star wasn’t the first flyby, and it won’t be the last. In fact, we’re on track for a much more dramatic close encounter in the not-too-distant future.

    “[Scholz’s Star] probably didn’t have a huge impact, but there should be many more stars that have passed through that are more massive,” astronomer Eric Mamajek of NASA’s Jet Propulsion Laboratory, whose 2015 paper in Astrophysical Journal Letters put Scholz’s Star on the map, tells Astronomy.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Astronomy is a magazine about the science and hobby of astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of the University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at the University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
  • richardmitnick 11:10 am on December 25, 2020 Permalink | Reply
    Tags: "40 years after Voyager scientists push for new missions to Uranus and Neptune", A new mission proposal named Trident [a mission to Neptune’s moon Triton] has been selected as one of four semifinalists for NASA’s Discovery Program., , Astronomy magazine, , , Beneath the atmospheres of both planets the mantles are mostly super-hot high-pressure global oceans of water; ammonia; and methane — essentially a liquid electrical conductor., , In 1781 Uranus became the first planet ever discovered using a telescope., , More than a dozen proposals have been offered for return missions to one or both ice giants., Neptune and Uranus are each encircled by a set of rings., Neptune is approximately 17 times Earth’s mass and has a core weighing only 1.2 Earth masses., , The planetary research community has been giving the ice giants the cold shoulder., The solid core of both planets is made of iron; nickel; and silicates., Uranus’ core is small- only 0.55 Earth masses- while the planet’s overall mass is around 14 Earth masses.   

    From Astronomy Magazine: “40 years after Voyager scientists push for new missions to Uranus and Neptune” 

    From Astronomy Magazine

    December 17, 2020 [Catching up.]
    Joel Davis

    Voyager 2 visited the mysterious and majestic ice giants almost a half-century ago. And the clock is ticking on a return visit.

    1
    In 1781, Uranus became the first planet ever discovered using a telescope. Nearly 200 years later, Voyager 2 became the first spacecraft to visit Uranus and Neptune, in 1986 and 1989 respectively.
    Credit: NASA/JPL.

    NASA/Voyager 2.

    The Space Age Blasted off when the Soviet Union launched the world’s first artificial satellite in 1957. Since then, humanity has explored our cosmic backyard with vigor — and yet two planets have fallen to the planetary probe wayside.

    In the 63 years since Sputnik, humanity has only visited Neptune and Uranus once — when Voyager 2 flew past Uranus in January 1986 and Neptune in August 1989 — and even that wasn’t entirely pre-planned. The unmitigated success of Voyager 1 and 2 on their original mission to explore Jupiter and Saturn earned the twin spacecrafts further missions in our solar system and beyond, with Neptune and Uranus acting as the last stops on a Grand Tour of the outer solar system.

    In the 31 years since Voyager 2 left the Neptune system in 1989 and began its interstellar mission, more than a dozen proposals have been offered for return missions to one or both ice giants.

    Heliosphere-heliopause showing positions of two Voyager spacecraft. Credit: NASA.

    So far, none have made it past the proposal stage due to lack of substantial scientific interest. Effectively, the planetary research community has been giving the ice giants the cold shoulder.

    But recently, exoplanet data began revealing the abundance of icy exoplanets in our galaxy “and new questions about solar system formation are bringing focus back to Uranus and Neptune,” says astronomer Candace Hansen.

    And it just so happens to be the perfect time to consider a return trip.

    2
    A new mission proposal, named Trident, has been selected as one of four semifinalists for NASA’s Discovery Program. The proposed trajectory of the spacecraft would take advantage of a gravitational “kick” from Jupiter to reach Neptune and its moon, Triton. Credit: Astronomy: Roen Kelly.

    Time to return

    The decision to aim Voyager 2 at the ice giants was made in 1981, and took advantage of a rare planetary alignment of the outer planets. During its flyby of Jupiter, Voyager 2 received a “kick” from the planet, slingshotting it onto the right path to Uranus and eventually Neptune. A similar gravity assist from Jupiter will be possible between 2029 and 2034.

    Voyager 2’s flyby of the ice giants returned a wealth of new knowledge about these frigid behemoths, succeeding beyond everyone’s wildest dreams. The spacecraft discovered new rings and new moons around both planets, found wild winds on Neptune when none were expected, and revealed that Neptune’s moon Triton was truly spectacular, hinting at the possibility of a subsurface ocean that could potentially support microbial life.

    Hansen, a member of the Voyager imaging team during the flybys of Uranus and Neptune, recently recalled two of Voyager’s many highlights: “the images of plumes or clouds (we don’t know which) on Triton. And of course, seeing Neptune’s Great Dark Spot for the first time.”

    But countless questions remain, such as how the planets formed around the early Sun and the cause of their extreme axial tilts compared to the rest of the planets in the solar system. For decades, scientists have clamored for a return to these majestic planets. And now might be the perfect time to plan a return visit, as key planetary alignments approach at the end of the decade. If we can beat the clock, an ice giant mission could help us unravel the lingering mysteries of these planets and provide new insight into their chilling beauty.

    3
    At a distance of only 175,000 miles (280,000 km), Voyager 2 captured these long-exposure images of Neptune’s faint rings.
    Credit: NASA/JPL.

    Migrating planets and screwy magnetospheres

    Uranus and Neptune are called ice giants, and rightly so. The planets circle the Sun at such great distances, receiving so little external heat, that their average temperatures are hundreds of degrees below freezing.

    As it turns out, ice giants are some of the most prevalent planets currently found in the universe, too. As some of the largest planets in a star system, they tend to be easier to spot when they transit their host star. However, current models say that ice giants should be an anomaly, as the window for them to form is narrow. The solar nebula — the cloud of gas and dust left over after the formation of a star from which planets are born — needs to be almost entirely dissipated for ice giants to snatch up the available gas and ice. They also first need to have substantial cores before they can accrete any that lingering gas and ice.

    Figuring out exactly how and where Neptune and Uranus formed could help scientists better understand the abundance of ice giants lurking in the universe. Computer simulations suggest that the low density of planetesimals and the weak solar gravity in the primordial outer solar system would have made it very difficult for the ice giants to form where they are today.

    And perhaps they didn’t. Like Jupiter and Saturn, Uranus and Neptune may have formed closer to the early Sun before, via gravitational processes, eventually migrating outward to their present positions.
    But how they formed isn’t the only strange aspect about our ice giants.

    3
    With a rotation axis tilted more than 90 degrees compared to its orbital plane, as well as a large magnetic axis tilt, Uranus also has a variable magnetic field (traced here in gold) and magnetosphere. Credit: NASA’s Scientific Visualization Studio/JPL NAIF.

    Uranus rolls. Really. It’s tilted at 97.8 degrees from vertical, greater than any planet except Venus (177.4 degrees). For one-quarter of its 84-year orbit, each pole on Uranus is in continuous sunlight. Current theories suggest a large planetesimal may have struck a glancing blow, flipping the planet on its side. This would also explain other mysteries, too, such as its strange magnetic field.


    A basic view of the Uranian magnetosphere when the rotation axis is perpendicular to the Uranus-Sun line and days and nights are of equal duration. Credit: NASA’s Scientific Visualization Studio/JPL NAIF.

    Magnetospheres are typically in line with a planet’s rotation, but Uranus’ is tipped at 59 degrees from the planet’s rotational axis and offset from its center by one-third the planet’s radius. The result is a magnetosphere that wobbles in a complex pattern as Uranus spins on its axis.

    4
    Neptune likewise has a highly tilted rotation axis and tilted magnetic axis. As a result, Neptune has a lopsided magnetic field (traced in gold) that twists and turns in complex patterns as the planet spins. Credit: NASA’s Scientific Visualization Studio/JPL NAIF.

    Similarly, Neptune’s magnetic field is tilted at 47 degrees from its axis and shifted away from the planet’s center by more than half the planet’s radius. Its magnetosphere traces a wild-looking corkscrew shape as the planet rotates.


    A basic view of the Neptunian magnetosphere when the southern side of the rotation axis is directed sunward (southern summer).
    Credit: NASA’s Scientific Visualization Studio/JPL NAIF.

    Scientists still don’t entirely understand these anomalous magnetospheres. They know that planetary magnetic fields are generated by internal dynamos, or conductive global mantle oceans. But with magnetic poles so skewed off-center, the exact cause of Uranus’ and Neptune’s screwy magnetospheres is, like their formation, still unknown.

    Magnificent blue marbles

    Though the planet’s strange magnetic fields and uncertain formation may have scientists scratching their heads, when Voyager 2 revealed the first images of the planets’ atmospheres, it took our collective breath away. The valuable flyby revealed some unexpected puzzles about the atmospheres and internal mechanics of both planets.

    6
    Theories suggest that deep within the mantles of both Neptune and Uranus, diamonds may fall to the planets’ rocky cores. Besides raining diamonds, the planets have some of the most extreme orbital tilts in the solar system, with Uranus essentially spinning on its side. Credit: Lunar and Planetary Institute.

    Their cloud tops are among the coldest places in the solar system, too: –371 degrees Fahrenheit (–224 degrees Celsius) for Uranus and about –361 F (–218 C) for Neptune. Only the surface of Pluto is colder.

    But despite receiving so little light from the Sun, Neptune has weather — and what weather! Wispy white clouds scoot above the planet, and in 1989, Voyager 2 clocked winds near a strange, previously unseen dark spot on Neptune, reaching 1,000 mph (1,609 km/h) — the strongest of any in the solar system. This spot, dubbed the Great Dark Spot, was a massive spinning storm the size of Earth. Since its discovery, the storm has faded, but new ones have appeared elsewhere on the planet. By studying these dark spots, scientist might find a window to Neptune’s lower atmosphere.

    Both ice giants have atmospheres made of mostly hydrogen and helium, with small amounts of methane. It is the methane gases, however, that give Uranus its beautiful aquamarine color, as methane absorbs red light. Neptune’s color, on the other hand, is a more vivid blue. While methane contributes to that, another elementary component is likely the cause of such an intense blue — but exactly which one remains uncertain.

    Beneath the atmospheres of both planets, the mantles are mostly super-hot, high-pressure global oceans of water, ammonia, and methane — essentially a liquid electrical conductor. Inside their mantles, there may exist a deep layer where water is broken down into a soup of hydrogen and oxygen ions. Thousands of miles beneath their surfaces, the pressure is so great that methane splits apart and hardens its carbon compound into diamond crystals that sink to the planets’ cores. Yes: It could be raining diamonds.

    The solid core of both planets is made of iron, nickel, and silicates. Neptune is approximately 17 times Earth’s mass and has a core weighing only 1.2 Earth masses. Uranus’ core is small, only 0.55 Earth masses, while the planet’s overall mass is around 14 Earth masses.

    While these facts are all well known, the internal heat of both planets presents much more of a conundrum. Uranus hardly radiates any heat at all compared to other planets in the solar system. Neptune, on the other hand, despite being 10 astronomical units (AU; where 1 AU is the average distance between Earth and the Sun) beyond Uranus, radiates 2.61 times as much energy as it receives from the Sun. The explanation for this could have to do with an ancient impact from a protoplanet which expelled most of Uranus’ heat. This would also explain the planet’s extreme tilt. But astronomers still don’t know if internal heat released by Neptune (or Uranus) varies seasonally. Another visiting spacecraft could provide more data.

    7
    This Hubble Space Telescope image showcases the four major rings surrounding Uranus, along with ten of its known satellites.
    Credit: NASA/JPL/STSCI.

    Rings: Thin, icy, and dusty

    When Voyager 2 flew by Uranus and Neptune, it didn’t just shine a light on the icy worlds; it gave us the first glimpses of their rings.

    Like all the giant planets in our solar system, Neptune and Uranus are each encircled by a set of rings. In 1977, James L. Elliot discovered five of Uranus’ rings, the first found around a planet other than Saturn. Further observations from Earth revealed four more and, when Voyager 2 reached the planet in 1986, a 10th ring was discovered. In total, 13 known rings circle the planet, varying in both thickness and opacity.

    Several of Uranus’ small moons appear to keep its rings constrained, acting as gravitational shepherds. Most of the rings are made of particles ranging in size from 8 inches to 66 feet (20 centimeters to 20 meters) in diameter, likely composed of water-ice mixed with radiation-produced organic matter. The rings are probably no more than 600 million years old, based on observations made by Voyager 2 of the planet’s exosphere, and they may be the remains from collisions of ancient moons.

    After discovering rings around Uranus, astronomers were eager to spy rings around its twin. While several claims were put forth, including the detection of incomplete arcs, it wasn’t until Voyager 2 reached Neptune that definitive rings were discovered. The planet’s five rings — Galle, Le Verrier, Lassell, Arago, and Adams — are named after astronomers who made important discoveries regarding the planet: Johann Gottfried Galle, Urbain Jean Joseph Le Verrier, and John Couch Adams all independently discovered the planet in 1846 using mathematics, making it the first planet found with calculations. François Arago suggested Le Verrier investigate the anomalies in Uranus’ motion, which hinted at Neptune’s existence, while William Lassell discovered Triton.

    As it turned out, the incomplete arcs previously detected were the densest parts of the Adams ring. The rings themselves have more dust-sized grains than Uranus’, such that much of the system resembles the faint rings of Jupiter. To even see the rings clearly, light from Neptune must be blocked.

    The lone flyby of the planets revealed rings previously unseen; a future mission could uncover even more about the fine structural detail of the ice giants’ ring systems and help pin down their age.

    8
    Uranus is host to 13 known rings and 27 moons. Miranda and Ariel are notable due to their unusual surfaces. Neptune has just five rings and 14 moons, the most famous of which is Triton. This distant moon circles Neptune in a retrograde orbit, or counter to the planet’s spin. Credit: Astronomy/Roen Kelly.

    Moons small and large

    The planets aren’t just surrounded by rings; over a dozen moons circle both Neptune and Uranus, and one moon may just give scientists reason to return to the ice giants.

    Uranus’ 27 moons include a generous sampling of mystery and marvel. For example, the surface of Miranda, a moon over seven times smaller than our Moon, looks like a cosmic patchwork quilt and includes a gorge 12 times deeper than the Grand Canyon. Meanwhile, Ariel may have the youngest surface of Uranus’ moons, possibly redone by recent low-impact collisions. Ariel is over twice the size of Miranda.

    9
    Miranda is the innermost of Uranus’ spherical moons and has one of the most extreme topographies of any object in the solar system. The only close-up images of Miranda are from the Voyager 2 flyby of Uranus in January 1986. Credit: NASA/JPL/USGS.

    Neptune, on the other hand, has 14 known moons. The two outermost, Neso and Psamathe, are incredible because of their miniscule size. Neso is a mere 37 miles (60 km) in diameter, 60 times smaller than the Moon. Psamathe is even tinier with a diameter of 25 miles (40 km). While not the smallest moons in the solar system (that position is currently held by Mars’ moon Deimos, which is just 7.6 miles [12.4 km] in diameter), Neso orbits the furthest from its host planet, at a little over 30 million miles (49 million km). It takes little Neso a whopping 27 years to make a single orbit around Neptune. Psamathe, on the other hand, orbits just shy of 30 million miles (48 million km) from the ice giant.

    10
    Triton has the coldest known surface in the solar system and is the only known satellite with a surface made of mostly nitrogen ice. This global color mosaic of the moon, taken by Voyager 2, indicates that it has a vast southern polar cap believed to contain methane, which was stained pink by sunlight. Credit: NASA/JPL/USGS.

    Neptune’s largest moon, Triton, is the planet’s standout satellite. The moon is bigger than Pluto and the only one of the solar system’s large moons with a retrograde orbit, meaning it circles Neptune in the opposite direction from the planet’s spin. Voyager 2 discovered that Triton is scattered with relatively young surface features, hosts active geysers, and even shows hints of a subsurface ocean. Scientists suspect that Triton is a captured Kuiper Belt object due to its strange orbit and surface, although an alternative method of capture during the early solar system when planets passed each other near enough to steal moons has been recently suggested.

    Triton has one of the more substantial atmospheres of the solar system moons, but it is still significantly thinner than Earth’s. Consisting of nitrogen, methane, and carbon monoxide, this atmosphere likely originated from volcanic activity. Besides Earth, Triton is only one of three solar system bodies known to currently be volcanically active. Evidence of ongoing geological activity points to the possibility of a subsurface ocean. As such, Triton was identified as one of the highest priority candidate ocean worlds for future missions by the NASA Outer Planets Assessment Group Roadmaps to Ocean World (ROW) group in the recent “NASA Roadmap to Ocean Worlds” report, which summarizes their findings. ROW provides a framework to guide the future of ocean world exploration over the next several decades.

    Triton earning this high priority may just be what it takes to get us back to the outer solar system so we can explore the ice giants once more.

    11
    Fittingly named after the son of Poseidon, Triton may be hiding an ocean world beneath its icy crust. The moon is also one of only four bodies in the solar system to be volcanically active. Credit: NASA/JPL-Caltech.

    Trident: A mission to Triton

    Under NASA’s Discovery Program, a new mission to the ice giants may be within reach. Started in 1992, the program provides scientists a chance to imagine innovative, low-cost ways to unlock the mysteries of the solar system.

    In August 2017, a Discovery proposal period began and a small group at JPL convened a two-day brainstorming session. The group produced the Trident proposal — a flyby mission to Triton. “The whole process went from concept to a real project remarkably quickly,” recalls co-author Karl Mitchell.

    The proposed Trident mission will pass within 310 miles (500 km) of the giant moon, close enough to move through its atmosphere. Trident plans to map Triton, characterize its active processes, and determine whether the moon has a magnetic field — which would strengthen the argument that the moon is hiding an ocean beneath its surface. To accomplish these tasks, Trident will need a host of instruments, including a magnetometer, both a narrow-angle and wide-angle camera, and a plasma spectrometer.

    In February, NASA selected the Trident proposal as one of four Discovery-class semifinalists.

    The team will visit NASA in February or March 2021 for an intensive review before the agency makes their final selection of which missions will fly.

    Hopefully Trident is one of them, as it’s time to return to the majestic ice giants and take the next steps in unraveling the mysteries of these enigmatic goliaths.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Astronomy is a magazine about the science and hobby of astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of the University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at the University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
  • richardmitnick 9:19 am on December 18, 2020 Permalink | Reply
    Tags: "Cosmic ingredients: How the universe forges elements", , Astronomy magazine, , , , , , R-process: rapid neutron-capture process, S-process: slow neutron-capture process, The R-process is nearly instantaneous - at least in astronomical terms., The R-process is very similar to the S-process except it’s much quicker., Through the R-process an iron atom can be transformed into uranium in less than a second.   

    From Astronomy Magazine: “Cosmic ingredients: How the universe forges elements” 

    From Astronomy Magazine

    December 14, 2020
    Mara Johnson-Groh

    1
    Now iconic image of two neutron stars colliding somewhere in the depths of space in this artist’s concept. In addition to generating gravitational waves, such an event can produce many heavy elements, including gold. Credit: University of Warwick/Mark Garlick.

    Carl Sagan once famously said: “We are made of star stuff.” He was referring to the origin of many elements — like the calcium in our bones and the iron in our blood — that are forged in the last breaths of dying stars.

    But while it’s true we are star stuff, that’s only half of the story.

    Some of the elements we know, like carbon and oxygen, are made in stars, but others — including all hydrogen, most helium, and a bit of lithium — were forged nearly 14 billion years ago through a process called Big Bang nucleosynthesis. It wasn’t until the first stars formed some 100 million years after the Big Bang that the universe began to diversify its element portfolio. And our understanding of exactly how it does that is only just being finalized.

    Cosmic alchemy

    The idea that smaller, lighter pieces of matter could be forged into heavier ones dates back to at least the ancient Greeks. But it wasn’t until the 1920s that scientists really began to understand the specifics.

    At the time, scientists were trying to figure out what powered the Sun. Astronomer Arthur Eddington first theorized that hydrogen atoms — the lightest element — could be squeezed together under immense temperature and pressure into helium — the second lightest element. This process, known as nuclear fusion, releases colossal amounts of energy.

    Over the following decades, scientists verified the mechanism, working out many of the details. And by the mid-20th century, astronomers had a good handle on how stars made elements lighter than iron.

    They deduced that during the prime years of their lives, stars steadily churn hydrogen into helium within their cores. And if a star is larger than about half the mass of the Sun, once it runs out of hydrogen in its core, it begins to collapse under its own uncontested gravity. This creates additional pressure in the star’s core, which sparks helium burning and can ultimately produce by-products such as carbon and oxygen. Stars more than twice the mass of the Sun that also have carbon and oxygen from their forbearers can produce nitrogen as well.

    Stars up to roughly eight times the mass of the Sun eventually reach a phase of their lives known as the asymptotic giant branch. This is where their cores become inactive, and helium and hydrogen burning migrates to the stars’ outer layers. At this stage, the stars begin the slow neutron-capture process. Also known as the S-process, this occurs in helium burning shells around stellar cores, which creates heavier elements like strontium, lead, and others.

    Eventually, these relatively low-mass stars collapse into dense objects known as white dwarfs. And as they do, they can expel supersonic winds, releasing shells of gas that create beautiful — albeit short-lived — planetary nebulae. This liberates the stars’ elemental creations into interstellar space, where some of the enriched material will be recycled into new stars and planetary systems.

    2
    Hydrogen and helium emerged after the Big Bang, forming stars. Heavier elements — up to iron — formed in supernovas. But astronomers now know the stuff that’s heavier than iron is created in neutron star mergers. Credit: Jennifer Johnson/ SDSS/ CC BY 2.0 (modified)/ Courtesy: CalTech.

    Explosive origins

    However, when a more massive star (greater than about eight solar masses) reaches the end of its life, it can explode as a core-collapse supernova. Such supernovae can leave behind neutron stars that produce highly neutron-rich winds.

    In these winds, additional elements are formed through the rapid neutron-capture process, or R-process. When the nuclei of existing atoms capture extra free neutrons, the resulting product can be radioactive — meaning it will decay into a different version of itself or a new element entirely — or it can remain stable.

    The R-process is very similar to the S-process, except it’s much quicker. The S-process can take decades or centuries to capture successive neutrons, with the entire elemental transformation taking tens of thousands of years. However, a supernova can produce roughly a billion billion billion neutrons per cubic inch, so the R-process is nearly instantaneous — at least in astronomical terms. For example, through the R-process, an iron atom can be transformed into uranium in less than a second.

    Astronomers also recently confirmed another suspected R-process site: merging neutron stars.

    Signatures of elements that are only created by the R-process were observed coming from the location of a confirmed neutron star merger picked up by gravitational waves. Even though such mergers are rarer than supernovae, astronomers now think that neutron star mergers are the primary sites of most heavy r-process elements. After all, this observed gravitational-wave event alone is expected to have produced an estimated three to 13 Earth-masses worth of gold.

    Now that astronomers know how the universe forges all (or at least most) of its elements, the next step is working to understand exactly how much of each element is produced through various processes, as well as where they tend to occur. By building on this knowledge, researchers ultimately hope it will allow them to easily probe the complex history of any galaxy by simply looking at the ratios of its elements.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Astronomy is a magazine about the science and hobby of astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of the University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at the University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
  • richardmitnick 8:51 am on December 18, 2020 Permalink | Reply
    Tags: "Is the multiverse theory science fiction or science fact?", , Astronomy magazine, , , , Parallel universes could exist whether cosmologists can prove it or not.   

    From Astronomy Magazine: “Is the multiverse theory science fiction or science fact?” 

    From Astronomy Magazine

    December 14, 2020
    Eric Betz

    Parallel universes could exist, whether cosmologists can prove it or not.

    1
    A multiverse consists of many separate and distinct universes, as depicted in this artist’s concept. Credit: Jaswe/Shutterstock.

    Do we live in a multiverse? Daydreamers and science-fiction authors have pondered parallel universes for as long as scientists have described our own.

    Our universe contains everything we know — from planets, stars, and galaxies to space and time itself. And it’s truly staggering in size, spanning some 93 billion light-years across, according to astronomers’ estimates. That’s more than our species could ever hope to explore.

    But what if our universe isn’t the only one? What if alternate universes are humming along undetected, right “next” to ours?

    Cosmologists call this idea the multiverse, and there’s good reason to consider the concept. Indeed, many of the best scientific models for the creation of our universe actually depend on the existence of a multiverse.

    Theories suggesting alternate universes

    The idea of a multiverse didn’t just get thrust onto society by imaginative sci-fi writers, it’s been born out of other premises, like string theory and quantum mechanics. Even the theory of cosmic inflation, which sits at the heart of astronomers’ current ideas about our cosmos, predicts the existence of a multiverse.

    A multiverse could be teeming with other universes that are nearly identical to ours — or they could be unimaginably different. Either way, the realms of parallel universes open up many interesting (and mind-boggling) possibilities.

    As many authors have envisioned over the years, if there are infinite other universes, then there are at least some that contain doppelgängers of yourself. But these alternate versions of you also might experience an entirely different physical reality, as the laws of nature aren’t necessarily the same for every universe.

    The four kinds of parallel universes

    According to MIT mathematician and cosmologist Max Tegmark, a parallel universe could come in four different flavors.

    A parallel universe could have nothing qualitatively new and different than our own universe.
    A parallel universe could have totally different fundamental laws of physics.
    A parallel universe could have the same fundamental laws of physics, but have started with different initial conditions.
    A parallel universe could have the same fundamental laws of physics, but different effective bylaws.

    Many scientists have dismissed the very idea of the multiverse over the years because of one simple fact: If you can’t leave our own universe, then there’s no way to prove that any other universes exist. However, not everyone agrees with that premise.

    Proof of a multiverse

    How would we prove that we live in a multiverse? If our universe collided with another, it would offer some evidence — though it’s unclear whether we would survive to study it. And some theorists have suggested that colliding universes could leave cold spots or hot spots on the cosmic microwave background (CMB), the afterglow of the Big Bang.

    CMB per ESA/Planck

    If so, we should be able to detect those spots with advanced sky surveys.

    Gravitational waves — ripples in the fabric of space-time — might also provide evidence to support the theory of cosmic inflation. The theory predicts that gravitational waves left over from the Big Bang could put tiny curls into the CMB, which some telescopes are actively searching for today.

    If researchers can spot such curls in the CMB — as they thought they did back in 2014 — it could ultimately boost support for the idea that there’s another you out there, going about their daily life in an alternate universe, proving sci-fi writers correct once again.

    Or, perhaps, not. Maybe we don’t each have countless extra-cosmic kin. And maybe that’s not such a bad thing.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Astronomy is a magazine about the science and hobby of astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of the University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at the University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
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