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  • richardmitnick 8:25 am on September 14, 2014 Permalink | Reply
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    From SPACE.com: “How Was the Sun Formed?” 2013 Elementary but still Important for Some 

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    SPACE.com

    January 17, 2013
    Nola Taylor Redd

    In a wide expanse of space, gravity drew dust and gas together to create the young solar system. The sun formed first from the vast material, with the planets close behind. But how did a sea of swirling particles become the brightest star in our sky?

    sun
    The Sun: Our Perfectly Average Middle Aged Star Credit: Space.com

    Although it may look empty, space is filled with gas and dust. Most of the material was hydrogen and helium, but some of it was made up of leftover remnants from the violent deaths of stars. Waves of energy traveling through space pressed clouds of such particles closer together, and gravity causes them to collapse in on themselves. As the material drew together, gravity caused it to spin. The spin caused the cloud to flatten into a disk like a pancake. In the center, the material clumped together to form a protostar that would eventually become the sun.

    The young protostar was a ball of hydrogen and helium not yet powered by fusion. Over the course of about fifty million years, the temperature and pressure of the material inside increased, jumpstarting the fusion of hydrogen that drives the sun today.

    The formation of the sun didn’t take up all of the cloud it was born from. What was left continued to orbit the star, while planets formed from the leftover material. The sun is an average-size star, not too big and not to small. Its size makes it an excellent star to orbit, as it is neither large and fast-burning nor small and dim.

    Several million years from now, the hydrogen inside of the sun will run out, and the star will swell up into a red giant with a radius extending to Earth’s orbit. The helium at its core will also be consumed. The star will never be hot enough to burn the oxygen and carbon that are left behind, so the sun will fizzle out and become a white dwarf.

    See the full article here.

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  • richardmitnick 5:58 am on September 13, 2014 Permalink | Reply
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    From SPACE.com: “Comets: Formation, Discovery and Exploration” 

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    SPACE.com

    November 15, 2010
    Charles Q. Choi

    Comets – Overview

    A comet is an icy body that releases gas or dust. They are often compared to dirty snowballs, though recent research has led some scientists to call them snowy dirtballs. Comets contain dust, ice, carbon dioxide, ammonia, methane and more. Some researchers think comets might have originally brought some of the water and organic molecules to Earth that now make up life here.

    Comets orbit the sun, but most are believed to inhabit in an area known as the Oort Cloud,

    oort
    Artists rendering of the Kuiper Belt and Oort Cloud.

    far beyond the orbit of Pluto. Occasionally a comet streaks through the inner solar system; some do so regularly, some only once every few centuries. Many people have never seen a comet, but those who have won’t easily forget the celestial show.

    halley
    Halley’s Comet as photographed May 8, 1910, by Dr. G.W. Ritchey using the 60-inch (1.5-meter) telescope at Mount Wilson Observatory, Calif., during the comet’s last appearance. The head of the comet and the beginning of its long tail are shown. Short, straight streaks are background stars. Credit: NASA/JPL

    Physical Characteristics

    The solid nucleus or core of a comet consists mostly of ice and dust coated with dark organic material, with the ice composed mainly of frozen water but perhaps other frozen substances as well, such as ammonia, carbon dioxide, carbon monoxide and methane. The nucleus might have a small rocky core.

    As a comet gets closer to the sun, the ice on the surface of the nucleus begins turning into gas, forming a cloud known as the coma.

    coma

    Radiation from the sun pushes dust particles away from the coma, forming a dust tail, while charged particles from the sun convert some of the comet’s gases into ions, forming an ion tail. Since comet tails are shaped by sunlight and the solar wind, they always point away from the sun.

    The nuclei of most comets are thought to measure 10 miles (16 km) or less. Some comets have comas that can reach nearly 1 million miles (1.6 million kilometers) wide, and some have tails reaching 100 million miles (160 million kilometers) long.

    We can see a number of comets with the naked eye when they pass close to the sun because their comas and tails reflect sunlight or even glow because of energy they absorb from the sun. However, most comets are too small or too faint to be seen without a telescope.

    Comets leave a trail of debris behind them that can lead to meteor showers on Earth. For instance, the Perseid meteor shower occurs every year between August 9 and 13 when the Earth passes through the orbit of the Swift-Tuttle comet.

    Orbital Characteristics

    Asteroids classify comets based on the durations of their orbits around the sun. Short-period comets need roughly 200 years or less to complete one orbit, long-period comets take more than 200 years, and single-apparition comets are not bound to the sun, on orbits that take them out of the solar system. Recently, scientist have also discovered comets in the main asteroid belt — these main-belt comets might be a key source of water for the inner terrestrial planets.

    ast
    The inner Solar System, from the Sun to Jupiter. Also includes the asteroid belt (the white donut-shaped cloud), the Hildas (the orange “triangle” just inside the orbit of Jupiter), the Jupiter trojans (green), and the near-Earth asteroids. The group that leads Jupiter are called the “Greeks” and the trailing group are called the “Trojans” (Murray and Dermott, Solar System Dynamics, pg. 107).

    Scientists think short-period comets, also known as periodic comets, originate from a disk-shaped band of icy objects known as the Kuiper belt beyond Neptune’s orbit, with gravitational interactions with the outer planets dragging these bodies inward, where they become active comets. Long-period comets are thought to come from the nearly spherical Oort cloud even further out, which get slung inward by the gravitational pull of passing stars.

    Some comets, called sun-grazers, smash right into the sun or get so close that they break up and evaporate.

    Naming

    In general, comets are named after their discoverer, either a person. For example, comet Shoemaker-Levy 9 got its name because it was the ninth short-periodic comet discovered by Eugene and Carolyn Shoemaker and David Levy. Spacecraft have proven very effective at spotting comets as well, so the names of many comets incorporate the names of missions such as SOHO or WISE.

    NASA SOHO
    NASA/SOHO

    NASA Wise Telescope
    NASA/WISE

    mc
    Comet McNaught C/2009 R1 was visible on June 6, 2010. Credit: Michael Jäger


    Formation

    Astronomers think comets are leftovers from the gas, dust, ice and rocks that initially formed the solar system about 4.6 billion years ago.

    Comet Life Cycle
    Departure
    Some comets are not bound to the sun, on orbits that take them out of the solar system.

    Extinction

    Comets lose ice and dust each time they come near the sun, leaving behind trails of debris. Eventually, they can lose all their ices, with some turning into fragile, inactive objects similar to asteroids.

    Breakup

    Other comets, upon losing all their ices, break up and dissipate into clouds of dust.

    Collisions

    The orbits comets take sometimes end with them colliding with planets and their moons. Many impact craters seen in the solar system were caused by such collisions.

    History

    In antiquity, comets inspired both awe and alarm, “hairy stars” resembling fiery swords that appeared unpredictably in the sky. Often, comets seemed to be omens of doom — the most ancient known mythology, the Babylonian “Epic of Gilgamesh,” described fire, brimstone, and flood with the arrival of a comet, and Emperor Nero of Rome saved himself from the “curse of the comet” by having all possible successors to his throne executed. This fear was not just limited to the distant past — in 1910, people in Chicago sealed their windows to protect themselves from what they thought was the comet’s poisonous tail.

    For centuries, scientists thought comets traveled in the Earth’s atmosphere, but in 1577, observations made by Danish astronomer Tycho Brahe revealed they actually traveled far beyond the moon. Isaac Newton later discovered that comets move in elliptical, oval-shaped orbits around the Sun, and correctly predicted that they could return again and again.

    Chinese astronomers kept extensive records on comets for centuries, including observations of Halley’s Comet going back to at least 240 BC, historic annals that have proven valuable resources for later astronomers.

    A number of recent missions have ventured to comets.NASA’s Deep Impact collided an impactor into Comet Tempel 1 in 2005 and recorded the dramatic explosion that revealed the interior composition and structure of the nucleus. In 2009, NASA announced samples the Stardust mission returned from Comet Wild 2 revealed a building block of life. The European Space Agency’s Rosetta is scheduled to orbit Comet Churyumov-Gerasimenko in 2014 and deploy a probe to make the first landing on a comet.

    deep
    NASA/Deep Impact

    NASA Stardust spacecraft
    NASA/Stardust

    Famous Comets

    Halley’s Comet is likely the most famous comet in the world, even depicted in the Bayeux Tapestry that chronicled the Battle of Hastings of 1066. It becomes visible to the naked eye every 76 years when it nears the sun. When Halley’s Comet zoomed near Earth in 1986, five spacecraft flew past it and gathered unprecedented details, coming close enough to study its nucleus, which is normally concealed by the comet’s coma. The roughly potato-shaped, nine-mile-long (15 km) contains equal part ice and dust, with some 80 percent of the ice made of water and about 15 percent of it consisting of frozen carbon monoxide. Researchers believe other comets are chemically similar to Halley’s Comet. The nucleus of Halley’s Comet was unexpectedly extremely dark black — its surface, and perhaps those of most others, is apparently covered with a black crust of dust over most of the ice, and it only releases gas when holes in this crust expose ice to the sun.

    The comet Shoemaker-Levy 9 collided spectacularly with Jupiter in 1994, with the giant planet’s gravitational pull ripping the comet apart for at least 21 visible impacts. The largest collision created a fireball that rose about 1,800 miles (3,000 km) above the Jovian cloudtops as well as a giant dark spot more than 7,460 miles (12,000 km) across — about the size of the Earth —and was estimated to have exploded with the force of 6,000 gigatons of TNT.

    A recent, highly visible comet was Hale-Bopp, which came within 122 million miles (197 million kilometers) of Earth in 1997. Its unusually large nucleus gave off a great deal of dust and gas — estimated at roughly 18 to 25 miles (30 to 40 kilometers) across — appeared bright to the naked eye.

    When Earth crosses the path of a comet, even if the comet hasn’t been around for a few years, leftover dust and ice can create increased numbers of meteors in what’s known as a meteor shower.

    See the full article here.

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  • richardmitnick 2:51 pm on September 12, 2014 Permalink | Reply
    Tags: , , , Auroras, , , , space.com   

    From SPACE.com: ” Solar Storms Are Bombarding Earth Now, Amped-up Auroras Possible” 

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    SPACE.com

    Two waves of solar material blown out by powerful sun eruptions this week are hitting the Earth now, and could amplify the aurora displays for observers in northern regions.

    aurora
    Images of the aurora australis and aurora borealis from around the world, including those with rarer red and blue lights

    Scientists with NOAA’s Space Weather Prediction Center in Boulder, Colorado, expected the first wave of solar flare particles — unleashed by a so-called coronal mass ejection, or CME, on Monday (Sept. 8) — to reach Earth Thursday night (Sept. 11). A second wave, this one caused by a massive solar flare on Wednesday, is due to arrive between Friday and early Saturday.

    cme
    NASA Captures Image of M1 Coronal Mass Ejection April 18, 2012

    flare
    On August 31, 2012 a long prominence/filament of solar material that had been hovering in the Sun’s atmosphere, the corona, erupted out into space at 4:36 p.m. EDT

    “We do expect these storm levels to cause significant auroral displays across much of the northern U.S. on Friday night,” SWPC Director Thomas Berger told reporters on Thursday. “With clear skies currently forecast for much of these regions, this could be a good opportunity for auroral sightings.”

    The enhanced auroras would likely be most visible across the northern tier U.S. states, along the U.S.-Canada border, as well as in New England, added SWPC program coordinator William Murtagh. Clear, dark skies far from city light pollution are vital to observe any auroras.

    The first of the two solar storm waves reached Earth late Thursday right on time, space weather center officials wrote in an update late Thursday. Also on Thursday, NASA released a new video of the X1.6 solar flare from its sun-watching Solar Dynamics Observatory, showing the event in two different wavelengths.

    Coronal mass ejections are powerful eruptions of super-hot plasma than can be blown out from the sun during major solar flares. This week, the an active sunspot known as AR2158 sun fired off a moderate M4.6 solar flare on Monday, followed by a much more powerful X1.6-class flare on Wednesday, Sept. 10. X-class flares are the most powerful flares the sun experiences.

    Sunspot AR2158 is about the size of between 10 and 20 Earths, but appears to be in the process of breaking up, Berger said. The huge X1.6 solar flare may have been its swan song as it breaks down, he added.

    spot
    This NASA image shows the active sunspot AR2158, which unleashed a massive X1.6 solar flare on Sept. 10, 2014, as it appeared on Sept. 8, when it fired off a moderate M4.6 solar flare. On the right, Jupiter and Earth are superimposed to give a sense of the sunspot’s size. Credit: NASA Solar Dynamics Observatory (Little SDO)

    The two solar flares this week were accompanied by coronal mass ejections, and both were aimed at Earth. When directly aimed at Earth, the most powerful solar flares — events stronger than the X1.6 storm on Wednesday — can pose a danger to satellites and astronauts in space, and interfere with communication, navigation and even power distribution surfaces on the Earth’s surface.

    Berger said that the two CMEs from this week’s solar storms could cause some radio and GPS navigation system hiccups, as well as voltage irregularities in power grids of the northern United States, but nothing too extreme.

    “We don’t expect any unmanageable impacts to national infrastructure from these solar events at this time, but we are watching these events closely,” Berger said.

    flare
    The huge X1.6-class solar flare is seen erupting from the sun in this three-wavelength composite image captured by NASA’s Solar Dynamics Obervatory on Sept. 10, 2014. The solar flare occurred at 1:45 p.m. ET. Credit: NASA Solar Dynamics Observatory (Little SDO)

    Berger did say that it is fairly rare for two significant coronal mass ejections to hit Earth head-on at nearly the same time. A minor radiation storm was detected from the solar flares, as well as temporary radio blackouts, space weather officials said.

    Space weather officials did say that the most intriguing aspect of this week’s solar flares are their potential for boosting this weekend’s northern lights displays.

    When charged particles from solar storms reach Earth, they are funneled to the polar regions by the planet’s magnetic field and can great so-called geomagnetic storms.

    A minor G1-class storm is underway now, with levels expected to rise to a potentially strong G3-class by Saturday evening, Berger said.

    When solar particles collide with the Earth’s upper atmosphere, they let create a glow that can be visible from the ground as auroral light. In the northern regions of Earth, this glow is known as the aurora borealis, or northern lights. In the south, it is called the aurora australis, or southern lights. Significant solar flares can amplify those displays into dazzling dances of ethereal light.

    See the full article, with videos, here.

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  • richardmitnick 2:17 pm on September 12, 2014 Permalink | Reply
    Tags: , DARPA, space.com   

    From SPACE.com: ” DARPA Wants to Test Satellite Repair Droids in Orbit” 

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    SPACE.com

    September 12, 2014
    Elizabeth Howell

    The United States military’s high-technology branch is hoping to test out on-orbit satellite servicing in orbit in the next five years.

    Satellites that sit in geostationary orbit, which is about 22,000 miles (36,000 kilometers) above the Earth, are traditionally used for communications and surveillance because the length of the orbit is approximately the same as Earth’s day. This allows a satellite to gaze at the same area of Earth around the clock.

    This location is too far away for conventional satellite servicing mission concepts, however, and at the end of the satellite’s lifespan it needs to be moved away from that orbital slot to make way for new missions. As such, the Defense Advanced Research Projects Agency (DARPA) is seeking some sort of a public-private partnership for satellite servicing.

    orb it

    The U.S. military’s Defense Advanced Research Projects Agency is considering adding DARPA-developed space robotic technology to commercial spacecraft to create a robotic service droid capable of repairing satellites in geostationary orbits 22,000 miles above Earth. Credit: Defense Advanced Research Agency

    The partnership would be for both commercial and military owners with satellites in that space, possibly saving money since new satellites wouldn’t need to be launched as often.

    “The ability to safely and cooperatively interact with satellites in GEO [geostationary orbit] would immediately revolutionize military and commercial space operations alike, lowering satellite
    construction and deployment costs and improving satellite lifespan, resilience and reliability,” DARPA officials wrote in a statement.

    DARPA has put out a request for information looking for “technical, security and business insights” to make this service possible.

    The agency is seeking technical information on a possible “robotic servicer” that would make use of previously developed DARPA space robotics.

    Ideally, the robot would be able to fix mechanical problems like antenna issues, or inspect spacecraft that had operational problems, providing more information to controllers on Earth. The servicer might even be able to move satellites into other orbits.

    Responses to the request for information are due by Nov. 3. To learn more about DARPA’s satellite servicing project requirements, read the full request for information.

    See the full article, with video, here.

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  • richardmitnick 3:39 pm on September 11, 2014 Permalink | Reply
    Tags: , , , , Hot Jupiters, space.com   

    From SPACE.com: “Mystery of ‘Hot Jupiter’ Planets’ Crazy Orbits May Be Solved” 

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    September 11, 2014
    Charles Q. Choi

    Giant alien planets known as “hot Jupiters” orbit their stars much closer than Mercury does the sun. But the mystery of the origins of hot Jupiters deepened when astronomers recently discovered the scorching orbits of these worlds are often bizarrely skewed, tilted when compared with the equators of their stars.

    orbit

    Now, scientists might have solved the mystery behind why hot Jupiters have such weird orbits— as these giant worlds drew close to their stars, they may have forced the stars to wobble chaotically.

    Hot Jupiters are gas giant planets, much like Saturn or Jupiter, that orbit extraordinarily close to their stars, at about one-tenth of the distance from Mercury to the sun. About 1 percent of sunlike stars host these roaster planets.

    Astronomers first discovered hot Jupiters about 20 years, and they are some of the alien worlds that scientists have seen most often since then. That’s because the size and proximity of these giant exoplanets to their parent stars mean they exert large gravitational tugs on their hosts that researchers can readily spot.

    Prior studies found that hot Jupiters could not have originated where they are currently found, since interference from the gravity and radiation of their stars would have destroyed any gas giants attempting to form that close. Instead, scientists have suggested that hot Jupiters were initially born farther away from their stars and later migrated inward, due perhaps to gravitational tugs from companion stars to their host stars located a few hundred astronomical units (AU) away. An astronomical unit is the average distance between the sun and Earth, about 93 million miles (150 million kilometers).

    When planets migrate toward their stars, previous research suggested these exoplanets should usually end up circling the equators of their stars, just as all of the major planets in the solar system do around the sun. However, in the past four or five years, astronomers have discovered that more than half of all hot Jupiters seen to date have orbits that are mysteriously inclined — that is, they are tilted in relation to their stars’ equators.

    These scorching, tilted orbits might result from the way hot Jupiters cause their stars to dance chaotically as the planets migrate inward, scientists believe.

    “We call hot Jupiters giant planets, but they’re very small compared to their stars, about a thousand times less mass, so it’s quite surprising such planets can cause such dramatic changes to their star’s spin,” said study co-author Dong Lai, an astrophysicist at Cornell University in Ithaca, New York.

    When a star and its planets are born from a spinning disk of gas and dust, they all generally rotate the same way, and the orbits of the planets all line up with the star’s equator. If a star is in a binary system, the gravitational influence of a companion star can make a planet migrate inward.

    In computer simulations involving planets with a range of masses and stars with a variety of rates of spin, the scientists found that as a planet comes near its host star, it can make the star’s axis of spin wobble in a complex and even unpredictable way. “We didn’t anticipate this chaotic behavior,” Lai told Space.com.

    The way the poles of spin of these stars can sway chaotically “is similar to other chaotic phenomena found in nature, such as weather and climate, where the outcome may depend sensitively on the initial conditions, the so-called ‘butterfly effect,'” Lai said. “You also see chaotic behavior in the direction of the axis of rotation of Mars. The way Mars’ axis of spin has wandered over time has had a huge impact on the climate of Mars.”

    Lai and graduate students Natalia Storch and Kassandra Anderson detailed their findings in the Sept. 12 issue of the journal Science.

    See the full article here.

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  • richardmitnick 6:13 pm on September 10, 2014 Permalink | Reply
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    From SPACE.com: “20-Year Mystery of the Universe’s Brightest Objects Solved” 

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    SPACE.com

    September 10, 2014
    Charles Q. Choi

    Quasars are the brightest objects in the universe, and display a mysterious diversity in their appearance that has puzzled astronomers for more than two decades.

    quasar
    A quasar, the brightest type of object in the universe, is seen releasing massive amounts of energy as stars are shredded near the supermassive black hole of a galaxy in this artistic illustration.
    Credit: NASA/JPL-Caltech

    Now, scientists find this mystery can be solved by looking at two simple features of quasars — how quickly matter is getting fed into the quasars and the direction from which the quasars are seen.

    Quasars are supermassive black holes up to billions of times the mass of the sun that live at the hearts of distant, massive galaxies. They release extraordinarily large amounts of light as they rip apart stars and gobble matter.

    Past studies of quasars have found that the physical properties of the objects follow definite, regular trends — for instance, a quasar’s size is linked with its mass. However, despite such trends, for some puzzling reason, quasars can vary greatly in appearance in visible and ultraviolet light.

    To help solve this mystery, scientists examined the largest sample of quasar observations yet — data from more than 20,000 quasars captured by the Sloan Digital Sky Survey. The collaboration’s statistical analyses revealed that the appearance of quasars could mostly be explained by two basic factors.

    SDSS Telescope
    SDSS Telescope at Apache Point Observatory

    “Our work solves a two-decade-long mystery in quasar research,” lead study author Yue Shen, an astronomer at the Carnegie Observatories in Pasadena, Calif.,told Space.com.

    The first factor is the so-called Eddington ratio — the luminosity of a quasar compared with its mass. This ratio predicts how quickly matter is falling into a quasar, and was long suspected to play a major role in why quasars often varied in appearance.

    The other factor is the direction from which astronomers look at a quasar, which influences how much they can see of the clouds of gas closest to the black hole. This fast-moving gas produces a broad range of wavelengths of light, greatly affecting a quasar’s appearance, and these findings suggest that these clouds are arranged in a flattened disk, explaining why the direction from which they are seen can matter so much.

    “Our findings have profound implications for quasar research,” Shen said in a statement. “This simple unification scheme presents a pathway to better understand how supermassive black holes accrete matter and interplay with their environments.”

    In addition, these findings will help improve future measurements of black hole masses, which in turn will help scientists better understand “the cosmic growth of supermassive black holes and their place in galaxy formation,” study co-author Luis Ho at the Kavli Institute for Astronomy and Astrophysics at Peking University said in a statement.

    Shen also noted there are several ongoing quasar surveys that will provide even more data “to expand the unification scheme established here.” For example, this future data will help yield insights on smaller black holes, “which are fainter, and were missed in earlier surveys,” he said.

    The research is detailed in the Sept. 11 edition of the journal Nature.

    See the full article here.

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  • richardmitnick 7:19 am on September 10, 2014 Permalink | Reply
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    From SPACE.com: “What Is the Fermi Paradox?” 

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    SPACE.com

    April 02, 2014
    Elizabeth Howell

    The Fermi Paradox seeks to answer the question of where the aliens are. Given that our star and Earth are part of a young planetary system compared to the rest of the universe — and that interstellar travel might be fairly easy to achieve — the theory says that Earth should have been visited by aliens already.

    As the story goes, Enrico Fermi (an Italian physicist) first came out with the theory with a casual lunchtime remark in 1950. The implications, however, have had extraterrestrial researchers scratching their heads in the decades since.

    “Fermi realized that any civilization with a modest amount of rocket technology and an immodest amount of imperial incentive could rapidly colonize the entire galaxy,” the Search For Extraterrestrial Intelligence (SETI) said on its website.

    “Within ten million years, every star system could be brought under the wing of empire. Ten million years may sound long, but in fact it’s quite short compared with the age of the galaxy, which is roughly ten thousand million years. Colonization of the Milky Way should be a quick exercise.”

    Plentiful planets

    It is true that the universe is incredibly vast and old. One estimate says the universe spans 92 billion light-years in diameter (while growing faster and faster). Separate measurements indicate it is about 13.82 billion light-years old. At first blush, this would give alien civilizations plenty of time to propagate, but then they would have a cosmic distance barrier to cross before getting too far into space.

    The sheer number of planets that we have found outside of our solar system, however, indicates that life could be plentiful. A November 2013 study using data from the Kepler Space Telescope suggested that one in five sun-like stars has an Earth-size planet orbiting in the habitable region of its star, the zone where liquid water would be possible. That zone is not necessarily an indication of life, as other factors, such as the planet’s atmosphere, come into play. Further, “life” could encompass anything from bacteria to starship-sailing extraterrestrials.

    NASA Kepler Telescope
    NASA/Kepler

    A few months later, Kepler scientists released a “planet bonanza” of 715 newly discovered worlds, pioneering a new technique called “verification by multiplicity.” The theory essentially postulates that a star that appears to have multiple objects crossing its face or tugging at it would have planets, as opposed to stars. (A multiple star system at such close proximity would destabilize over time, the technique postulates.) Using this will accelerate the pace of exoplanet discovery, NASA said in 2014.

    exo

    Our understanding of astrobiology (life in the universe) is just at a beginning, however. One challenge is these exoplanets are so far away that it is next to impossible for us to send a probe out to look at them. Another obstacle is even within our own solar system, we haven’t eliminated all the possible locations for life. We know from looking at Earth that microbes can survive in extreme temperatures and environments, giving rise to theories that we could find microbe-like life on Mars, the icy Jovian moon Europa, or perhaps Saturn’s Enceladus or Titan.

    All of this together means that even within our own Milky Way Galaxy — the equivalent of the cosmic neighborhood — there should be many Earth-size planets in habitable zones that could host life. But what are the odds of these worlds having starfarers in their bounds?

    Life: plentiful, or rare?

    The odds of intelligent life are estimated in the Drake Equation, which seeks to figure out the number of civilizations in the Milky Way that seek to communicate with each other. In the words of SETI, the equation (written as N = R* • fp • ne • fl • fi • fc • L) has the following variables:

    N = The number of civilizations in the Milky Way galaxy whose electromagnetic emissions are detectable.

    R* = The rate of formation of stars suitable for the development of intelligent life.

    fp = The fraction of those stars with planetary systems.

    ne = The number of planets, per solar system, with an environment suitable for life.

    fl = The fraction of suitable planets on which life actually appears.

    fi = The fraction of life bearing planets on which intelligent life emerges.

    fc = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space.

    L = The length of time such civilizations release detectable signals into space.

    None of these values are known with any certainty right now, which makes predictions difficult for astrobiologists and extraterrestrial communicators alike.

    There is another possibility that would dampen the search for radio signals or alien spacecraft, however: that there is no life in the universe besides our own. While SETI’s Frank Drake and others suggested there could be 10,000 civilizations seeking communications in the galaxy, a 2011 study later published in the Proceedings of the National Academy of Sciences suggested that Earth could be a rare bird among planets.

    It took at least 3.5 billion years for intelligent life to evolve, the theory by Princeton University researchers David Spiegel and Edwin Turner said, which indicates it takes a lot of time and luck for this to happen.

    Other explanations for the Fermi paradox include extraterrestrials “spying” on Earth, ignoring it altogether, visiting it before civilization arose, or visiting it in a way that we can’t detect.

    See the full article here.

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  • richardmitnick 8:16 pm on September 9, 2014 Permalink | Reply
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    From SPACE.com: ” Cool! Planet-Like Object May Have Once Been as Hot as a Star” 

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    SPACE.com

    September 09, 2014
    Nola Taylor Redd

    A cool newfound planet-like object may have started its life as hot as a star.

    New research shows that the object, known as WISE J0304-2705 and classified as a Y dwarf, may have begun its evolution with a temperature as hot as a red dwarf star before settling on its present temperature, which is similar to Venus.

    stars

    “Our measurements suggest that this Y dwarf may have a composition and/or age characteristic of one of the galaxy’s oldest members,” David Pinfield, of the University of Hertfordshire, and lead researcher of the study detailing the findings, said in a statement. “This means its temperature evolution could have been rather extreme.”

    A peculiar object

    WISE J0304-2705 is part of the newly discovered “Y dwarf” class of stars, the coolest of the brown dwarf objects. Brown dwarfs are often referred to as “failed stars” because, despite their substantial size, they fall short of the necessary mass to begin the hydrogen fusion that powers stellar objects.

    The new planet-like object has a mass between 20 and 30 Jupiters, ranking it in size between planets and small stars. Unlike the rocky Earth, the Y dwarf has a gas exterior much like Jupiter.

    Pinfield and his team identified the Y dwarf with NASA’s WISE Observatory, then followed up with some of the largest ground-based telescopes to better understand its characteristics. These observations revealed that the object may have an ancient origin, undergoing large temperature changes over the course of its life. Its unusual features led the scientists to classify it as “peculiar.”

    NASA Wise Telescope
    NASA/Wise

    “The ground-based measurements were very challenging, even with the large telescopes,” team member Mariusz Gromadzki, of the Millennium Institute of Astrophysics in Chile, said in the same statement. “It was exciting when the results showed just how cool this object was, and that it was unusual.”

    If the new object is ancient, it would have spent the first 20 million years of its life with a temperature of at least 5,100 degrees Fahrenheit (2,800 degrees Celsius), similar to red dwarf stars. By the time 100 million years had passed, it would have cooled to about 2,700 F (1,500 C), allowing silicate clouds to condense in its atmosphere.

    After a billion years, it would have cooled to temperatures around 1,800 F (1,000 C), cool enough for methane gas and water vapor to dominate in its atmosphere. Today, the would-be star barely reaches temperatures high enough to boil water, with a surface hitting 200 to 300 F (100 to 150 C), a range lying between that of Earth and Venus.

    Discovered in 2011, the Y dwarf class extends the range of brown dwarfs to as cold as minus 10 F (minus 23 C). Y dwarfs have no lower temperature limit, so even cooler objects may exist, including more unusual bodies.

    See the full article here.

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  • richardmitnick 1:29 pm on September 9, 2014 Permalink | Reply
    Tags: , , , , Mars Exploration, space.com   

    From SPACE.com: “Mars Probes from US and India Arrive at Red Planet This Month” 

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    SPACE.com

    September 09, 2014
    Elizabeth Howell

    The planet Mars is about to have some company. Two new spacecraft, one from the United States and the other from India, are closing in on the Red Planet and poised to begin orbiting Mars by the end of this month.

    The U.S.-built probe, NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, is expected to enter orbit around Mars on Sept. 21. Just days later, on Sept. 24, India’s Mars Orbiter Mission (MOM) orbiter is due to make its own Mars arrival when it enters orbit. Both MOM and MAVEN launched to space in 2013.

    NASA Mars MAVEN
    NASA/Mars MAVEN

    mom
    India’s Mars Orbiter Mission (MOM) orbiter

    MAVEN is the first mission devoted to probing the Martian atmosphere, particularly to understand how it has changed during the planet’s history.

    Before that happens, however, the spacecraft must burn its engines to go into orbit around the planet, and pass a commissioning phase while taking a few precautions for a “low-risk” situation where a comet will pass fairly close to Mars.

    “We’ve been developing MAVEN for about 11 years, and it comes down to a 33-minute rocket burn on Sept. 21,” MAVEN principal investigator Bruce Jakosky, of the University of Colorado, Boulder, told Space.com.

    The spacecraft can change tracks as late as 6 hours before entering orbit, but right now, it is so close to the correct path that a planned orbital maneuver on Sept. 12 won’t be needed, Jakosky said.

    Comet Siding Spring will pass near Mars on Oct. 19, and around that time, MAVEN will take a break from its commissioning to do observations of the comet and the planet’s upper atmosphere. Although not much dust is predicted to result from the event, as a precaution, controllers will turn off nonessential instruments and move the solar panels edge-on to the dust. The spacecraft will also be behind Mars for 20 minutes during the comet’s closest approach.

    One of MAVEN’s primary scientific tasks will be to figure out how the Martian atmosphere changed during the planet’s 4.5-billion-year history.

    Several NASA spacecraft have found extensive evidence that water once flowed on the planet. For water to have flowed on Mars, the planet would have required a thicker atmosphere. But why and how the atmosphere got thinner, to the way it is now, is one question that puzzles scientists.

    MAVEN is expected to last at least one Earth year, but with careful use of fuel, it could last a decade — long enough for controllers to watch the upper atmosphere change through almost an entire 11-year cycle of solar activity.

    Most of Mars’ water disappeared about 3.5 billion years ago, Jakosky said, and there will be two approaches for MAVEN to figure out how the atmosphere played into that.

    One approach will be to look at the atmosphere today and try to extrapolate its changes to what it used to be billions of years ago. However, one complication of that approach is that the sun’s output has changed over time. Early in the solar system’s history, the sun’s total output was 30 percent less than it is today. Therefore, Earth and Mars could have been colder, but the solar wind and ultraviolet energy would have been more intense.

    The second approach will be to look at the ratio of stable isotopes (element types) in the atmosphere, specifically the ratio of hydrogen to its heavier cousin, deuterium. Over time, the sun pushes lighter elements out of the atmosphere, leaving the heavier ones behind.

    Scientists already have gained a pretty firm understanding of the past deuterium-hydrogen ratio by examining known Martian meteorites and older Martian minerals that NASA rovers probed on the surface, Jakosky said. The next step will be to get more information on today’s conditions, to make comparisons.

    “It’s a powerful way to determine the history of the atmosphere,” he said. “We’re hoping that will be one of the early results coming out of MAVEN.”

    The Indian Space Research Organization’s Mars Orbiter Mission is India’s first mission to Mars and is designed to search for elusive methane in Mars’ atmosphere from orbit. Over the years, different orbital and surface missions have found variable amounts of the gas, which can be produced by nonbiological or biological means.

    MOM is expected to last six to 10 months near Mars, and has five instruments on board. The spacecraft and all of its payloads are in good health, ISRO said in a Facebook update on Aug. 30.

    One of the mission’s greatest challenges will be to fire the liquid propulsion engine after it sat idle for nearly 300 days in space. The engine is required to bring the spacecraft into Mars’ orbit. Media reports indicate that India plans to do a test fire of the engine on Sept. 22.

    If the Indian space agency is successful in reaching Mars, it will be the fourth entity to have done so, following the Soviet Union, the United States and the European Space Agency.

    See the full article here.

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  • richardmitnick 6:46 pm on September 8, 2014 Permalink | Reply
    Tags: , , , , Europa, , space.com, Subduction   

    From SPACE.com: “Jupiter’s Moon Europa May Have Plate Tectonics Just Like Earth” 

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    SPACE.com

    September 08, 2014
    Mike Wall

    Jupiter’s icy moon Europa, regarded as perhaps the solar system’s best bet to host alien life, keeps getting more and more interesting.

    eur
    Scientists have found evidence of an active plate tectonics system within the ice shell of Jupiter’s moon Europa. Earth has long been thought to be the only solar system body with plate tectonics.
    Credit: NASA/JPL/Ted Stry

    Big slabs of ice are sliding over and under each other within Europa’s ice shell, a new study suggests. The Jovian satellite may thus be the only solar system body besides Earth to possess a system of plate tectonics.

    “From a purely science or geological perspective, this is incredible,” study lead author Simon Kattenhorn of the University of Idaho told Space.com. “Earth may not be alone. There may be another body out there that has plate tectonics. And not only that, it’s ice!” [Photos: Europa, Mysterious Icy Moon of Jupiter]

    plates
    Artist’s concept of the subduction process thought to be occurring on Jupiter’s moon Europa, showing how a cold outer portion of Europa’s ice shell moved into the warmer shell interior and was ultimately absorbed. A “subsumption band” was created at the surface in the overriding plate, alongside which cryolavas may have erupted.
    Credit: Noah Kroese, I.NK

    The new results come less than a year after plumes of water vapor were spotted erupting from Europa’s south polar region. That find excited astrobiologists a great deal, because it suggested that a robotic probe may be able to sample the moon’s subsurface ocean of liquid water at a distance, without even touching down.

    “There have been a lot of recent exciting discoveries [about Europa],” Kattenhorn said. “All taken together, as NASA starts thinking about future missions, I’m hoping it will be pretty clear: This [Europa] is the obvious choice.”

    Missing puzzle pieces

    Kattenhorn and co-author Louise Prokter, of Johns Hopkins University’s Applied Physics Laboratory, studied photos of Europa taken by NASA’s Galileo spacecraft, which orbited Jupiter from 1995 until 2003.

    gal
    NASA/Galileo

    The researchers used the images to reconstruct the recent geological history of a 52,000-square-mile (134,000 square kilometers) swath of Europa — an area about the size of the state of Alabama. They noticed that the region changed over time, with some surface features becoming mismatched relative to the architecture captured in earlier images.

    plate
    False-color image of Europa’s trailing northern hemisphere, where subduction zones indicative of a system of plate tectonics are thought to exist.
    Credit: NASA/JPL/University of Arizona

    “It was very clear that you could reconstruct the original picture simply by moving plates around,” Kattenhorn said, comparing the duo’s approach to assembling a jigsaw puzzle.

    Further, there was a gap in this reconstructed picture, as if a large puzzle piece had fallen off the table. In a sense, that’s probably what did happen, Kattenhorn said.

    “In this case, the big chunk had actually moved down underneath the adjacent plate and was forever lost, recycled into the interior” of Europa’s ice shell, he said.

    That chunk was indeed big, about the size of the state of Massachusetts, Kattenhorn added.

    Plate tectonics

    Kattenhorn and Prokter think this phenomenon of one plate sliding under another, which is known as subduction, is the most likely explanation for the disappearing puzzle piece. They cite several lines of supporting evidence, including potential “cryolavas” of water ice near the plate boundary. (On Earth, volcanism is common along subduction zones.)

    If the scientists’ interpretation — laid out in a study published online today (Sept. 7) in the journal Nature Geoscience— is correct, planetary science textbooks will have to be rewritten.

    “Plate tectonics has been thought to be unique to our world,” Michelle Selvans, of the Smithsonian National Air and Space Museum, wrote in an accompanying News and Views piece in the same issue of Nature Geoscience.

    “Subduction zones, convergent boundaries where one tectonic plate slides under another and is recycled into the Earth’s mantle, are unique to plate tectonic systems,” Selvans wrote. “Although Mercury, Venus and Marsshow clear signs of tectonic activity, such as systems of thrust faults and rift valleys, none of these rocky planets have been convincingly shown to have a system of moving tectonic plates, either today or in the past.”

    An active system of plate tectonics could also explain two puzzling facts about Europa, Kattenhorn said: 1) why its surface is so young (less than 90 million years, as estimated by meteorite-impact rates), and 2) how the moon accommodates the creation of new ice on its shell, which has been observed previously. (Europa isn’t getting any bigger, so some process must be balancing out the production of new material.)

    “From my perspective, that’s pretty exciting, that we’ve addressed these two really important questions about Europa,” Kattenhorn said.

    He and Prokter said Europa likely has a system of cold, brittle plates moving around above convecting warmer ice. The mechanisms behind Europan plate tectonics are unclear at the moment, Kattenhorn said, stressing the need for modeling work. But tidal heating generated by the tug of Jupiter’s immense gravity, the same phenomenon that keeps Europa’s interior ocean from freezing up, may be one of the ultimate drivers, he added.

    zone
    Close-up view of a possible zone of plate spreading on Europa, showing internal striations related to spreading and bilateral symmetry about a central axis. Older geological features can be matched perfectly to either side of the spreading zone. (This image focuses on a different region of Europa than the one analyzed for the Nature Geoscience paper published on Sept. 7, 2014.)
    Credit: NASA/JPL

    Implications for life?

    info
    Scientists are eager to learn if Europa’s huge subsurface ocean harbors alien life. See how Jupiter’s icy moon Europa works in this SPACE.com infographic.
    Credit: by Karl Tate, Infographics Artist

    Some scientists think plate tectonics were essential to the rise of life on Earth. For example, the idea goes, the movement of plates replenishes nutrients and helps stabilize the planet’s climate by recycling carbon.

    So it’s natural to wonder if Europan plate tectonics may make the icy moon more habitable for simple lifeforms, Selvans wrote.

    “Perhaps Europa and Earth are even more uniquely similar: It is tempting to note the correlation between the existence of both life and plate tectonics on Earth and wonder if the latter might not be a requirement of the former,” she wrote.

    Europa’s ice shell is thought to be 12 to 19 miles (20 to 30 kilometers) thick, and subducting plates likely dive down only a mile so, Kattenhorn said. Subduction, therefore, probably doesn’t take any nutrients or other complex molecules from the surface down into the ocean immediately.

    But this could happen indirectly and over longer periods of time via convection, he added.

    “As with all convection, what goes up must go down as well,” Kattenhorn said. “One can imagine that some of that material may ultimately, just by virtue of being in a convective system, work its way downward. Whether that ultimately comes into contact with the ocean is an important question.”

    And there may be pockets of liquid water within the ice shell relatively close to the surface, perhaps close enough to be reached by a subducting Europan plate, he added.

    “People who are thinking about habitable environments — certainly not my field of expertise — that would probably be something very interesting for them to think about,” Kattenhorn said.

    See the full article here.

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