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  • richardmitnick 8:29 am on September 11, 2020 Permalink | Reply
    Tags: "Nearby red dwarf star not so quiet and life-friendly after all", , , , , , EarthSky, Red dwarf star Gliese 887, The nearest star to our solar system Proxima Centauri is a red dwarf.   

    From Arizona State University via EarthSky : “Nearby red dwarf star not so quiet and life-friendly after all” 


    From Arizona State University

    via

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    EarthSky

    September 11, 2020
    Paul Scott Anderson

    Astronomers say the nearby red dwarf star Gliese 887 appears to have more dangerous flare activity than first believed. This could make life tough – but maybe not impossible – on its family of super-Earth planets.

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    Artist’s concept of Gliese 887b and Gliese 887c orbiting their red dwarf star. A new study shows that the host star is not as inactive as first thought, and radiation from solar flares could endanger the planets. Image via Mark Garlick/ University of Göttingen.

    Exoplanets – worlds orbiting other stars – are common around red dwarf stars, which shouldn’t be too surprising since red dwarfs, in turn, are the most common stars in our galaxy. These stars are typically very active, emitting powerful solar flares, putting any otherwise habitable planets at risk. But one red dwarf in particular known to have planets, Gliese 887 (aka GJ 887 or Lacaille 9352), seemed to be quieter than most, with less flare activity. This was good news for the possibility of any of its super-Earth planets being able to support life, but now it seems those planets might not be quite as safe as first thought, astronomers at Arizona State University (ASU) have announced.

    The findings were published in Research Notes of the AAS on July 28, 2020.

    From the submitted research note:

    “GJ 887 has been spotlighted for the apparently gentle space environment it provides to its recently discovered planets. In 27 days of optical monitoring by the Transiting Exoplanet Survey Satellite (TESS), the star exhibited no detectable flares. Ultraviolet observations reveal a different story. Two high-contrast flares occurred in just 2.8 hr of far-ultraviolet monitoring by the Hubble Space Telescope (HST). Solar scalings indicate these flares were X-class or larger events, generally associated with coronal mass ejections on the sun. Hundreds of events of equal or greater energy likely occurred during the TESS monitoring, but produced optical contrasts too small to be detected. Strong yet optically undetectable ultraviolet flares like these could dominate the high energy emission of all M stars throughout their lives, impacting the photochemistry and erosion of atmospheres on orbiting planets.”

    Gliese 887 had previously been monitored by TESS, which is now actively searching for new exoplanets after the Kepler Space Telescope mission ended.

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

    NASA/MIT TESS replaced Kepler in search for exoplanets.

    The star was observed continuously for 27 days, and in that time, no flares were seen. That seemed unusual for a red dwarf, but it also meant that maybe its planets wouldn’t be decimated by solar radiation as much as first thought.

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    As depicted in this illustration, red dwarf stars are volatile, emitting powerful solar flares. The intense radiation could make planets uninhabitable, and even strip them of their atmospheres. Image via NASA/ ESA/ D. Player (STScI)/ Arizona State University.

    Those conclusions may have been a bit premature, however. Parke Loyd and Evgenya Shkolnik of ASU’s School of Earth and Space Exploration weren’t quite convinced the star was really that quiet. They decided to take a look at archived data for the star from Hubble, and their suspicions were confirmed. They found that Gliese 887 actually does flare, on an hourly basis.

    So how did they determine this, if no flares had been seen by TESS?

    They looked at images and data of the star in ultraviolet (UV) light. TESS had observed the star in regular visible light, like we see with our own eyes. But the flares on red dwarf stars can show up in ultraviolet light, even when visible light shows nothing. The photons (“particles” of light or the smallest discrete amount of electromagnetic radiation) in ultraviolet light have much more energy than those of visible light, making it easier to see the flares. Since no flares had been seen by TESS, it was assumed the star had far fewer of them than most other red dwarfs. The flares were there, however, but only visible in ultraviolet light. Shkolnik said in a statement:

    “It is fascinating to know that observing stars in normal optical light (as the TESS mission does) doesn’t come close to telling the whole story. The damaging radiation environment of these planets can only fully be understood with ultraviolet observations, like those from the Hubble Space Telescope.”

    Whether red dwarfs can host life-bearing worlds is of great interest to scientists, since there are so many of them and many, if not most, seem to have planets. As Loyd said:

    “If the genesis of life on a planet is more or less a roll of the dice, then M stars are rolling those dice far more than any other type of star.”

    Just this past July, astronomers announced two (and maybe three) super-Earth exoplanets – larger and more massive than Earth, but smaller and less massive than Neptune – orbiting Gliese 887, called Gliese 87b and Gliese 87c. The star is very close to us, cosmically speaking, at only 11 light-years away. The two known planets orbit close to the inner edge of the star’s habitable zone, the region where temperatures could allow liquid water to exist.

    An earlier study from 2014 suggested that virtually every red dwarf has at least one planet. Those results were obtained from analyzing data from two high-precision planet surveys – the High Accuracy Radial Velocity Planet Searcher (HARPS) and the Ultraviolet and Visual Echelle Spectrograph (UVES) – both operated by the European Southern Observatory in Chile.

    ESO/HARPS at La Silla


    ESO 3.6m telescope & HARPS at Cerro LaSilla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    UVES spectrograph mounted on the VLT at the Nasmyth B focus of UT2.

    By combining the data, the team was able to detect signals that were not strong enough to be seen clearly in the data from either instrument alone.

    The volatility of red dwarfs with their powerful flares is thought to be a significant impedance to the possible evolution of life on any planets orbiting them. But how true is that, really? There’s no question the radiation from such flares is a big problem, but it may not mean that life is always impossible.

    The nearest star to our solar system, Proxima Centauri, is a red dwarf, and has at least one Earth-mass planet orbiting it, Proxima Centauri b.

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker.

    A new study from researchers at the University of Buenos Aires-CONICET (IAFE) in Argentina last February suggested that life – at least microbial – could still manage to survive on that planet, if it ever existed to begin with. According to astrobiologist Ximena Abrevaya:

    “Our experiments suggest that life “as we know it” could cope with highly UV irradiated environments under conditions that cannot be found on Earth.”

    The researchers modeled different atmospheres for the planet, and found that even those without ozone could still sufficiently protect life on the surface from the radiation. The same would be true for nitrogen- and carbon dioxide-rich atmospheres. They also found that even without the shielding of an atmosphere, the UV radiation reaching the surface of Proxima Centauri b during temporarily more quiescent conditions would be negligible from a biological point of view. Even in a worst-case scenario, a fraction of the microorganisms could still survive.

    These results are promising for the possibility of life on planets orbiting red dwarfs. The high doses of radiation, higher than any on Earth, may not always be a death knell for living organisms after all. So despite these stars’ “violent” reputation, it may well be that many habitable worlds will still be found around red dwarfs.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition


    ASU is the largest public university by enrollment in the United States. Founded in 1885 as the Territorial Normal School at Tempe, the school underwent a series of changes in name and curriculum. In 1945 it was placed under control of the Arizona Board of Regents and was renamed Arizona State College. A 1958 statewide ballot measure gave the university its present name.
    ASU is classified as a research university with very high research activity (RU/VH) by the Carnegie Classification of Institutions of Higher Education, one of 78 U.S. public universities with that designation. Since 2005 ASU has been ranked among the Top 50 research universities, public and private, in the U.S. based on research output, innovation, development, research expenditures, number of awarded patents and awarded research grant proposals. The Center for Measuring University Performance currently ranks ASU 31st among top U.S. public research universities.

    ASU awards bachelor’s, master’s and doctoral degrees in 16 colleges and schools on five locations: the original Tempe campus, the West campus in northwest Phoenix, the Polytechnic campus in eastern Mesa, the Downtown Phoenix campus and the Colleges at Lake Havasu City. ASU’s “Online campus” offers 41 undergraduate degrees, 37 graduate degrees and 14 graduate or undergraduate certificates, earning ASU a Top 10 rating for Best Online Programs. ASU also offers international academic program partnerships in Mexico, Europe and China. ASU is accredited as a single institution by The Higher Learning Commission.

     
  • richardmitnick 8:29 am on August 21, 2020 Permalink | Reply
    Tags: "Hayabusa2 re-entry capsule approved to land in Australia", , , , , EarthSky, JAXA-Japan Aerospace Exploration Agency, Near-Earth asteroid Ryugu   

    From JAXA-Japan Aerospace Exploration Agency via EarthSky: “Hayabusa2 re-entry capsule approved to land in Australia” 

    From JAXA-Japan Aerospace Exploration Agency

    via

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    EarthSky

    August 21, 2020
    Deborah Byrd

    JAXA/Hayabusa 2 Credit: JAXA/Akihiro Ikeshita

    The Japan Aerospace Exploration Agency said this week that it has now been officially informed that its Hayabusa2 space capsule – carrying precious dust captured from the surface of near-Earth asteroid Ryugu – is approved for landing in Australia.

    On February 22, 2019, the Hayabusa2 spacecraft of the Japan Aerospace Exploration Agency (JAXA) touched down briefly on near-Earth asteroid 162173 Ryugu and fired a bullet into the asteroid’s surface. The spacecraft collected a sample of dust puffed up during the maneuver, and now the spacecraft – carrying its precious cargo of an asteroid sample within a capsule on board – is headed back to Earth. The spacecraft will sweep past Earth, and the capsule will drop to Earth’s surface via parachute on December 6, 2020. JAXA said in an announcement on August 19, 2020, that it has now been officially informed that the capsule is approved for landing in Australia. JAXA said:

    “The Hayabusa2 re-entry capsule will return to Earth in South Australia on December 6, 2020 (Japan Time and Australian Time). The landing site will be the Woomera Prohibited Area. The issuance of the AROLSO [Authorization of Return of Overseas-Launched Space Object] gave a major step forward for the capsule recovery.”

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    Photograph of the full disc of the asteroid 162173 Ryugu, as it appeared to the Hayabusa2 spacecraft at 03:50 UTC on 26 June 2018. The photograph was taken by the spacecraft’s Optical Navigation Camera – Telescopic (ONC-T) at a distance of 20 kilometres (12 miles). 162173 Ryugu is the 23rd minor planet studied by a spacecraft in-situ, and is the target of the second ever sample-return mission to an asteroid, Hayabusa2.

    Hayabusa2 was launched from Earth on December 3, 2014. The spacecraft rendezvoused with asteroid Ryugu on June 27, 2018. The mission follows an earlier JAXA Hayabusa mission (the name means Peregrine falcon), which, in 2010, returned samples from asteroid 25143 Itokawa, the first-ever asteroid to be the target of a sample return mission and the only other mission so far to have returned asteroid samples to Earth.

    Hayabusa2 surveyed Ryugu for a year and a half. It left the asteroid with the precious sample safe inside its capsule in November, 2019.

    After Hayabusa2 flies past Earth to deliver its sample capsule in late 2020, it is expected to retain 30 kg (66 lb) of xenon propellant, which can be used to extend its service and to fly by new targets to explore. As of August 2020, there are two scenarios under consideration for a mission extension. First, a Venus flyby in 2024 would set up the spacecraft for a November 2029 encounter with a small, quickly spinning near-Earth asteroid called 2001 AV43. During the flyby, Hayabusa2 could also conduct infrared observations of Venus. Alternatively, the spacecraft could be sent toward a rendezvous with another near-Earth asteroid and another fast rotator – 1998 KY26 – in July 2031.

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    A live webcast showed Hayabusa2 scientists nervously monitoring Hayabusa2’s February 22, 2019 touchdown on distant asteroid Ryugu.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Japan Aerospace Exploration Agency (JAXA) was born through the merger of three institutions, namely the Institute of Space and Astronautical Science (ISAS), the National Aerospace Laboratory of Japan (NAL) and the National Space Development Agency of Japan (NASDA). It was designated as a core performance agency to support the Japanese government’s overall aerospace development and utilization. JAXA, therefore, can conduct integrated operations from basic research and development, to utilization.

    In 2013, to commemorate the 10th anniversary of its founding, JAXA created the corporate slogan, “Explore to Realize,” which reflects its management philosophy of utilizing space and the sky to achieve a safe and affluent society.

    JAXA became a National Research and Development Agency in April 2015, and took a new step forward to achieve optimal R&D achievements for Japan, according to the government’s purpose of establishing a national R&D agency.

     
  • richardmitnick 1:39 pm on August 18, 2020 Permalink | Reply
    Tags: "Meet the Andromeda galaxy, , , , , EarthSky, , the closest large spiral", ,   

    From EarthSky: “Meet the Andromeda galaxy, the closest large spiral” 

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    From EarthSky

    Originally August 18, 2019
    Re-presented August 18, 2020

    Bruce McClure

    The Andromeda galaxy is the closest big galaxy to our Milky Way. At 2.5 million light-years, it’s the most distant thing you can see with the eye alone. Now is the time to look for it.

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    The Andromeda Galaxy with 2 of its satellite galaxies, via Flickr user Adam Evans.

    Although several dozen minor galaxies lie closer to our Milky Way, the Andromeda galaxy is the closest large spiral galaxy to ours. Excluding the Large and Small Magellanic Clouds, which can’t be seen from northerly latitudes, the Andromeda galaxy – also known as Messier 31 – is the brightest galaxy you can see. At 2.5 million light-years, it’s also the most distant thing visible to your unaided eye.

    Magellanic Clouds ESO S. Brunier

    To the eye, this galaxy appears as a smudge of light larger than a full moon.

    When to look for the Andromeda Galaxy. From mid-northern latitudes, you can see Messier 31 – also called the Andromeda galaxy – for at least part of every night, all year long. But most people see the galaxy first around northern autumn, when it’s high enough in the sky to be seen from nightfall until daybreak.

    In late August and early September, begin looking for the galaxy in mid-evening, about midway between your local nightfall and midnight.

    In late September and early October, the Andromeda galaxy shines in your eastern sky at nightfall, swings high overhead in the middle of the night, and stands rather high in the west at the onset of morning dawn.

    Winter evenings are also good for viewing the Andromeda galaxy.

    If you are far from city lights, and it’s a moonless night – and you’re looking on a late summer, autumn or winter evening – it’s possible you’ll simply notice the galaxy in your night sky. It looks like a hazy patch in the sky, as wide across as a full moon.

    But if you look, and don’t see the galaxy – yet you know you’re looking at a time when it’s above the horizon – you can star-hop to find the galaxy in one of two ways. The easiest way is to use the constellation Cassiopeia. You can also use the Great Square of Pegasus.

    History of our knowledge of the Andromeda galaxy. At one time, the Andromeda galaxy was called the Great Andromeda Nebula. Astronomers thought this patch of light was composed of glowing gases, or was perhaps a solar system in the process of formation.

    It wasn’t until the 20th century that astronomers were able to resolve the Andromeda spiral nebula into individual stars. This discovery lead to a controversy about whether the Andromeda spiral nebula and other spiral nebulae lie within or outside the Milky Way.

    In the 1920s Edwin Hubble finally put the matter to rest, when he used Cepheid variable stars within the Andromeda galaxy to determine that it is indeed an island universe residing beyond the bounds of our Milky Way galaxy.

    Andromeda and Milky Way in context. The Andromeda galaxy and our Milky Way galaxy reign as the two most massive and dominant galaxies within the Local Group of Galaxies.

    Local Group. Andrew Z. Colvin 3 March 2011

    The Andromeda Galaxy is the largest galaxy of the Local Group, which, in addition to the Milky Way, also contains the Triangulum Galaxy and about 30 other smaller galaxies.

    Both the Milky Way and the Andromeda galaxies lay claim to about a dozen satellite galaxies. Both are some 100,000 light-years across, containing enough mass to make billions of stars.

    Astronomers have discovered that our Local Group is on the outskirts of a giant cluster of several thousand galaxies, which astronomers call the Virgo Cluster.

    Virgo Supercluster NASA

    We also know of an irregular supercluster of galaxies, which contains the Virgo Cluster, which in turn contains our Local Group, which in turn contains our Milky Way galaxy and the nearby Andromeda galaxy. At least 100 galaxy groups and clusters are located within this Virgo Supercluster. Its diameter is thought to be about 110 million light-years.

    Laniakea supercluster. From Nature The Laniakea supercluster of galaxies R. Brent Tully, Hélène Courtois, Yehuda Hoffman & Daniel Pomarède at http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html. Milky Way is the red dot.

    The Virgo Supercluster is thought to be one of millions of superclusters in the observable universe.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 11:32 am on August 18, 2020 Permalink | Reply
    Tags: "Earth’s night sky as Milky Way and Andromeda merge", , , , , EarthSky, Messier 33 aka the Triangulum galaxy – will also play a role.,   

    From EarthSky: “Earth’s night sky as Milky Way and Andromeda merge” 

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    From EarthSky

    August 18, 2020
    Deborah Byrd

    Billions of years from now, Earth’s night sky will change as the Andromeda galaxy rushes toward a merger with the Milky Way.

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    Andromeda galaxy actual size? Yes. This image truly depicts what the night sky would look like if the Andromeda galaxy – the galaxy next door – were brighter. Original background shot of the moon by Stephen Rahn. Andromeda galaxy image via NASA. Composite photo by Tom Buckley-Houston.

    The image above is making the rounds on social media this week. It’s true. The neighboring Andromeda galaxy occupies about the width of 6 moon-diameters on our sky’s dome. But, of course, the galaxy isn’t nearly this bright. You need a dark sky to see it, and, even then, it’s a barely visible fuzzy patch of light. In order to appear as bright as in the image above, the Andromeda galaxy would need to be closer. If it were close enough to look so bright, it would appear even bigger on our sky’s dome. And that’s going to happen someday! The Andromeda galaxy is currently racing toward our Milky Way at a speed of about 70 miles (110 km) per second. Ultimately, the two galaxies will merge. Between now and that eventual merger, any beings alive on Earth will see the Andromeda galaxy get bigger and bigger and BIGGER in our night sky.

    The Andromeda galaxy is now about 2.5 million light-years away from us. The artist’s concepts below, released by NASA in 2012, show what will happen to Earth’s night sky as the Andromeda galaxy hurtles toward us.

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    This series of illustrations shows the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy.
    First Row, Left: Present day.
    First Row, Right: In 2 billion years the disk of the approaching Andromeda galaxy is noticeably larger.
    Second Row, Left: In 3.75 billion years Andromeda fills the field of view.
    Second Row, Right: In 3.85 billion years the sky is ablaze with new star formation.
    Third Row, Left: In 3.9 billion years, star formation continues.
    Third Row, Right: In 4 billion years Andromeda is tidally stretched and the Milky Way becomes warped.
    Fourth Row, Left: In 5.1 billion years the cores of the Milky Way and Andromeda appear as a pair of bright lobes.
    Fourth Row, Right: In 7 billion years the merged galaxies form a huge elliptical galaxy, its bright core dominating the nighttime sky.
    Image via NASA/ ESA/ Z. Levay and R. van der Marel, STScI/ T. Hallas/ A. Mellinger.

    The descriptions above are based on painstaking Hubble Space Telescope measurements of the motion of the Andromeda galaxy, followed by computer modeling of the inevitable future collision between the two galaxies. A series of studies published in 2012 showed that – rather than glancing off each other, as merging galaxies sometimes do – our Milky Way galaxy and the Andromeda galaxy will in fact merge to form a single big elliptical, or football-shaped, galaxy.

    The Milky Way and Andromeda galaxies won’t be the only ones involved in this merger. As shown in the video below, the other large galaxy in our Local Group of galaxies – Messier 33, aka the Triangulum galaxy – will also play a role. In this video, you’ll recognize the Triangulum galaxy as the smaller object near the Andromeda and Milky Way galaxies. Although the Triangulum galaxy likely won’t join the merger, it may at some point strike our Milky Way while engaged in a great cosmic dance with the two larger galaxies.

    Across the universe, galaxies are colliding with each other. Astronomers see galactic collisons – or their aftermaths – through their telescopes. In some ways, when a galactic merger takes place, the two galaxies are like ghosts; they simply pass through each other. That’s because stars inside galaxies are separated by such great distances. Thus the stars themselves typically don’t collide when galaxies merge.

    That said, the stars in both the Andromeda galaxy and our Milky Way will be affected by the merger. The Andromeda galaxy contains about a trillion stars. The Milky Way has about 300 billion stars. Stars from both galaxies will be thrown into new orbits around the newly merged galactic center. For example, according to scientists involved in the 2012 studies:

    “It is likely the sun will be flung into a new region of our galaxy …
    And yet, they said,
    .. our Earth and solar system are in no danger of being destroyed.”

    How about life on Earth? Will earthly life survive the merger? Astronomers say that the luminosity, or intrinsic brightness, of our sun is due to increase steadily over the next 4 billion years. As the sun’s luminosity increases, the amount of solar radiation reaching the Earth will also increase. It’s possible that – by 4 billion years from now – the increase in the Earth’s surface temperature will have caused a runaway greenhouse effect, perhaps similar to that going on now on the planet next door, Venus, whose surface is hot enough to melt lead. No one expects to find life on Venus. Likewise, it seems likely life on Earth will not exist 4 billion years from now.

    What’s more, our sun is evolving, too. It’s expected to become a red giant star eventually. The sun’s outer layers will swell into the space of the solar system so that Earth itself is swallowed by the sun’s outer layers. That’s expected to happen about 7.5 billion years from now.

    Perhaps by that time, some earthly inhabitants will have become space-faring. Perhaps we’ll have left Earth, and even our solar system.

    4
    Artist’s concept of a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, as it’ll unfold over the next several billion years. In this image, representing Earth’s night sky in 3.75 billion years, Andromeda (left) fills the field of view and begins to distort the Milky Way with tidal pull. Image via NASA/ ESA/ Z. Levay and R. van der Marel, STScI/ T. Hallas/ A. Mellinger.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 8:06 am on August 17, 2020 Permalink | Reply
    Tags: "What are lightning sprites?", EarthSky   

    From EarthSky: “What are lightning sprites?” 

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    From EarthSky

    August 17, 2020
    Deborah Byrd

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    View at EarthSky Community Photos. | Stephen Hummel, who works at McDonald Observatory in West Texas, captured this fleeting lightning sprite – aka a red sprite – on July 2, 2020. McDonald Observatory is spearheading a Dark Skies Initiative in its region. Stephen commented, “Dark skies help you see faint objects like sprites.” Thank you, Stephen!

    U Texas at Austin McDonald Observatory, Altitude 2,070 m (6,790 ft)

    Did you know that lightning sprites – like the one captured in the image above – exist above some thunderstorms? Sprites aren’t terribly well known, except to meteorologists, nature photographers and others who study the skies. They aren’t especially rare, but they’re fleeting. They’re not easy to capture on film. Lightning sprites are electrical discharges high in Earth’s atmosphere. They’re associated with thunderstorms, but they’re not born in the same clouds that send us rain. Thunderstorms – in fact all earthly weather – happen in the layer of Earth’s atmosphere called the troposphere, which extends from Earth’s surface to about 4 to 12 miles (about 6 to 19 km) up. Lightning sprites – also known as red sprites – happen in Earth’s mesosphere, up to 50 miles (80 km) high in the sky.

    So when you’re standing on Earth’s surface and you spot one, it appears relatively small, even though, in fact, sprites can be some 30 miles (50 km) across. As Matthew Cappucci of the Washington Post’s Capital Weather Gang said in an article about lightning sprites last year:

    “Imagine one electrical discharge spanning the distance from Baltimore to Washington, D.C.”

    Cappucci also commented:

    “Although sprites are poorly understood, atmospheric electrodynamicists have figured out the basics behind their formation. Sprites are often triggered by a strong, positive bolt of ordinary lightning near the ground. They’re thought to be a balancing mechanism that the atmosphere uses to dispense charges vertically. It’s a quick process that takes less than a tenth of a second.

    That’s what makes hunting for sprites so tough. Blink and you’ll miss them.”

    The fleeting aspect of lightning sprites probably explains why – when people first see photos of them – they’re surprised that such a strange-looking weather phenomenon even exists.

    Also, it hasn’t been that many years since lightning sprites were confirmed. In the 20th century, pilots spoke of “flashes above thunderstorms.” Lightning sprites as we know them today weren’t captured and their intricate structure didn’t begin to be recorded on film until as late as 1989, when experimental physicist John R. Winckler (1916-2001) happened to capture one while testing a low-light television camera.

    Today, people around the world routinely capture photos of lightning sprites. You’ll find many photos of them in this gallery from SpaceWeather.com.

    To photograph a sprite, you need a dark sky and a clear view toward a distant thunderstorm. The sky needs to be dark, because you’ll be taking long exposures; too much stray light in your sky will wash out your photo and make capturing sprites impossible. One of the most successful sprite photographers in the U.S., and likely in the world, is Paul M. Smith. He captured the sprite below in June 2020. You can follow him on Twitter: @PaulMSmithPhoto. Or find him on YouTube.

    Want more photos of lightning sprites? Try these:

    Lightning sprites over the Andes in early 2020, from Yuri Beletsky

    Lightning sprites over Oklahoma in 2018, from Paul Smith

    Captures of elusive red sprites from the International Space Station

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 9:49 am on July 25, 2020 Permalink | Reply
    Tags: "Astronomers ponder Odd Radio Circles in space", , , , , EarthSky, ,   

    From Western Sydney University via EarthSky: “Astronomers ponder Odd Radio Circles in space” 

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    From Western Sydney University

    via

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    EarthSky

    July 24, 2020
    Paul Scott Anderson

    Scientists in Australia have discovered a strange new phenomenon in deep space – “Odd Radio Circles” – that appear in radio telescope images as mysterious circles or rings.

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    (Norris et al., arXiv, 2020) via Science Alert

    Our universe is full of weird and wonderful things, and astronomers keep making new and increasingly bizarre discoveries. The latest discovery has them going in circles, literally. Using a radio telescope, astronomers at Western Sydney University in Australia spotted four unusual objects in deep space that look like a ring or bubble. They’ve dubbed them Odd Radio Circles or ORCs because they are circular … and so odd.

    The researchers have submitted a new paper to Nature Astronomy, where it is currently awaiting peer review.

    As explained in the paper’s abstract:

    “We have found an unexpected class of astronomical objects which have not previously been reported, in the Evolutionary Map of the Universe Pilot [EMU]survey, using the Australian Square Kilometre Array Pathfinder telescope (ASKAP).

    Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Australian Mid West. ASKAP consists of 36 identical parabolic antennas, each 12 metres in diameter, working together as a single instrument with a total collecting area of approximately 4,000 square metres.

    The objects appear in radio images as circular edge-brightened discs about one arc-minute diameter, and do not seem to correspond to any known type of object. We speculate that they may represent a spherical shock wave from an extra-galactic transient event, or the outflow, or a remnant, from a radio galaxy viewed end-on.”

    In other words, they don’t know what they’ve found. They can only speculate.

    Radio telescopes are able to “see” various kinds of circular objects in space. What makes these ORCs unique? From the paper:

    “Circular features are well-known in radio astronomical images, and usually represent a spherical object such as a supernova remnant, a planetary nebula, a circumstellar shell [composed of circumstellar dust], or a face-on disc such as a protoplanetary disk or a star-forming galaxy.

    They may also arise from imaging artifacts [lens flares] around bright sources …

    Here we report the discovery of a class of circular feature in radio images that do not seem to correspond to any of these known types of object or artifact, but rather appear to be a new class of astronomical object.”

    Scientists first noticed the ORCs in images from the late 2019 Pilot Survey of the Evolutionary Map of the Universe (EMU). The images were collected using ASKAP, one of the world’s most highly sensitive radio telescope arrays.

    First, one faint circle was seen in the images, then another. Then the astronomers found a third. Were they glitches? One or two maybe, but three?

    Then, a fourth ORC was found in archived data from 2013. In that case, the Giant Metrewave Radio Telescope (GMRT) had been used, a few years before ASKAP began observing.

    GMRT

    Giant Metrewave Radio Telescope, located near Pune (Narayangaon) in India, operated by the National Centre for Radio Astrophysics, a part of the Tata Institute of Fundamental Research, Mumbai

    ORC 1 and ORC 2 were then later observed again using using yet another telescope, the Australian Telescope Compact Array (ATCA). All of these observations showed that these were real objects, not just glitches with ASKAP.

    STCA

    CSIRO Australia Compact Array, six radio telescopes at the Paul Wild Observatory, is an array of six 22-m antennas located about twenty five kilometres (16 mi) west of the town of Narrabri in Australia.

    So scientists now accepted that these strange objects were real phenomena, ones that had not been seen before. But what were they?

    We still don’t know.

    What we do know is that all four ORCs are found at high galactic latitudes, well away from the plane of the galaxy, the flat part containing our sun and most other Milky Way stars. And, as observed, the ORCs are about one arcminute in size (a 60th of a degree or about 3% of the size of the moon).

    Scientists still don’t know how far away they are. That’s a big gap in our knowledge about these objects, since, for many objects, the distance away can provide clues to the objects’ identities.

    The ORCs are visible only at radio wavelengths, with radio telescopes. They can’t be seen at all in X-ray, optical or infrared wavelengths. Two of the ORCs have a galaxy near the center of the circles, but the other two don’t. ORC 3 appears as a uniform disk, while the other three look more like rings.

    Could they be supernova remnants or planetary nebulae, two other well-known kinds of cosmic rings? There’s a similarity, but the researchers say no. They are unlikely to be supernova remnants because three of the ORCs were found in a very small patch of sky. That would imply they were very common, and there would need to be at least 50,000 such supernova remnants in our galaxy to make the numbers work. But astronomers only know of about 350.

    So what else could they be? One idea is that they might be huge circular shockwaves from some massive event(s), outside the galaxy. As the researchers noted in the paper:

    “Several such classes of transient events, capable of producing a spherical shock wave, have recently been discovered, such as fast radio bursts, gamma-ray bursts and neutron star mergers. However, because of the large angular size of the ORCs, any such transients would have taken place in the distant past.

    It is also possible that the ORCs represent a new category of a known phenomenon, such as the jets of a radio galaxy or blazar when seen end-on, down the ‘barrel’ of the jet. Alternatively, they may represent some remnant of a previous outflow from a radio galaxy.”

    Since the discovery of these first four ORCs, the researchers have identified six other candidate ORCs that are fainter.

    The ORCs are a fascinating new mystery for astronomers. For those with a truly speculative turn of mind, it might be natural to wonder if they could be artificial in origin. Right now, however, there’s no way to determine that possibility. For now, the ORCs are considered to be most likely natural phenomena. Stay tuned, as astronomers continue to probe for answers.

    See the full article here.

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 10:41 am on July 22, 2020 Permalink | Reply
    Tags: "A powerful 7.8-magnitude quake struck Alaska last night", , , , , EarthSky, , ,   

    From EarthSky: “A powerful 7.8-magnitude quake struck Alaska last night” 

    1

    From EarthSky

    July 22, 2020
    Deborah Byrd

    The quake happened around 10:15 p.m. Tuesday night 7.21.20, according to clocks in Alaska. A tsunami warning along coastal Alaska – which was later rescinded – sent some residents to higher ground.

    1
    The July 21, 2020, 7.8-magnitude earthquake struck off the coast of the Alaskan Peninsula, about 17 miles (27 km) deep. Image via USGS.

    According to Alaska Public Media, residents across coastal Alaska – from Homer to Unalaska – woke to the sounds of sirens and phone alerts last night, warning them of a possible tsunami. Many quickly left home, moving to higher ground. The warnings followed a 7.8-magnitude earthquake – a very powerful earthquake – that struck off coastal Alaska at around 10:15 p.m., local time, on Tuesday, July 21, 2020. The earthquake was centered offshore, 60 miles (98 km) south-southeast of Perryville, Alaska, according to the U.S. Geological Survey (USGS). All tsunami warnings and advisories were canceled early Wednesday morning, according to the National Weather Service.

    The Associated Press reported:

    “Hundreds wore masks against the spread of the coronavirus as they gathered in shelters.”

    Kodiak Police Sgt. Mike Sorter told the Associated Press early Wednesday morning:

    “No reports of any damage. No injuries were reported. Everything is nominal.”

    There have been multiple, smaller aftershocks since the main quake.

    __________________________________

    Earthquake Alert

    1

    Earthquake Alert

    Earthquake Network projectEarthquake Network is a research project which aims at developing and maintaining a crowdsourced smartphone-based earthquake warning system at a global level. Smartphones made available by the population are used to detect the earthquake waves using the on-board accelerometers. When an earthquake is detected, an earthquake warning is issued in order to alert the population not yet reached by the damaging waves of the earthquake.

    The project started on January 1, 2013 with the release of the homonymous Android application Earthquake Network. The author of the research project and developer of the smartphone application is Francesco Finazzi of the University of Bergamo, Italy.

    Get the app in the Google Play store.

    3
    Smartphone network spatial distribution (green and red dots) on December 4, 2015

    Meet The Quake-Catcher Network

    QCN bloc

    Quake-Catcher Network

    The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

    After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

    The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

    The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

    There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

    Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

    USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

    If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

    BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

    Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

    Below, the QCN Quake Catcher Network map
    QCN Quake Catcher Network map

    ShakeAlert: An Earthquake Early Warning System for the West Coast of the United States

    The U. S. Geological Survey (USGS) along with a coalition of State and university partners is developing and testing an earthquake early warning (EEW) system called ShakeAlert for the west coast of the United States. Long term funding must be secured before the system can begin sending general public notifications, however, some limited pilot projects are active and more are being developed. The USGS has set the goal of beginning limited public notifications in 2018.

    Watch a video describing how ShakeAlert works in English or Spanish.

    The primary project partners include:

    United States Geological Survey
    California Governor’s Office of Emergency Services (CalOES)
    California Geological Survey
    California Institute of Technology
    University of California Berkeley
    University of Washington
    University of Oregon
    Gordon and Betty Moore Foundation

    The Earthquake Threat

    Earthquakes pose a national challenge because more than 143 million Americans live in areas of significant seismic risk across 39 states. Most of our Nation’s earthquake risk is concentrated on the West Coast of the United States. The Federal Emergency Management Agency (FEMA) has estimated the average annualized loss from earthquakes, nationwide, to be $5.3 billion, with 77 percent of that figure ($4.1 billion) coming from California, Washington, and Oregon, and 66 percent ($3.5 billion) from California alone. In the next 30 years, California has a 99.7 percent chance of a magnitude 6.7 or larger earthquake and the Pacific Northwest has a 10 percent chance of a magnitude 8 to 9 megathrust earthquake on the Cascadia subduction zone.

    Part of the Solution

    Today, the technology exists to detect earthquakes, so quickly, that an alert can reach some areas before strong shaking arrives. The purpose of the ShakeAlert system is to identify and characterize an earthquake a few seconds after it begins, calculate the likely intensity of ground shaking that will result, and deliver warnings to people and infrastructure in harm’s way. This can be done by detecting the first energy to radiate from an earthquake, the P-wave energy, which rarely causes damage. Using P-wave information, we first estimate the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and a warning is provided to local populations. The method can provide warning before the S-wave arrives, bringing the strong shaking that usually causes most of the damage.

    Studies of earthquake early warning methods in California have shown that the warning time would range from a few seconds to a few tens of seconds. ShakeAlert can give enough time to slow trains and taxiing planes, to prevent cars from entering bridges and tunnels, to move away from dangerous machines or chemicals in work environments and to take cover under a desk, or to automatically shut down and isolate industrial systems. Taking such actions before shaking starts can reduce damage and casualties during an earthquake. It can also prevent cascading failures in the aftermath of an event. For example, isolating utilities before shaking starts can reduce the number of fire initiations.

    System Goal

    The USGS will issue public warnings of potentially damaging earthquakes and provide warning parameter data to government agencies and private users on a region-by-region basis, as soon as the ShakeAlert system, its products, and its parametric data meet minimum quality and reliability standards in those geographic regions. The USGS has set the goal of beginning limited public notifications in 2018. Product availability will expand geographically via ANSS regional seismic networks, such that ShakeAlert products and warnings become available for all regions with dense seismic instrumentation.

    Current Status

    The West Coast ShakeAlert system is being developed by expanding and upgrading the infrastructure of regional seismic networks that are part of the Advanced National Seismic System (ANSS); the California Integrated Seismic Network (CISN) is made up of the Southern California Seismic Network, SCSN) and the Northern California Seismic System, NCSS and the Pacific Northwest Seismic Network (PNSN). This enables the USGS and ANSS to leverage their substantial investment in sensor networks, data telemetry systems, data processing centers, and software for earthquake monitoring activities residing in these network centers. The ShakeAlert system has been sending live alerts to “beta” users in California since January of 2012 and in the Pacific Northwest since February of 2015.

    In February of 2016 the USGS, along with its partners, rolled-out the next-generation ShakeAlert early warning test system in California joined by Oregon and Washington in April 2017. This West Coast-wide “production prototype” has been designed for redundant, reliable operations. The system includes geographically distributed servers, and allows for automatic fail-over if connection is lost.

    This next-generation system will not yet support public warnings but does allow selected early adopters to develop and deploy pilot implementations that take protective actions triggered by the ShakeAlert notifications in areas with sufficient sensor coverage.

    Authorities

    The USGS will develop and operate the ShakeAlert system, and issue public notifications under collaborative authorities with FEMA, as part of the National Earthquake Hazard Reduction Program, as enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2.

    For More Information

    Robert de Groot, ShakeAlert National Coordinator for Communication, Education, and Outreach
    rdegroot@usgs.gov
    626-583-7225

    Learn more about EEW Research

    ShakeAlert Fact Sheet

    ShakeAlert Implementation Plan

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 7:53 am on July 19, 2020 Permalink | Reply
    Tags: "A nova, , , , briefly visible in southern skies", , EarthSky   

    From EarthSky: “A nova, briefly visible in southern skies” 

    1

    From EarthSky

    July 19, 2020
    Deborah Byrd

    Astronomers have spotted a classical nova outburst in a type of variable star that involves a white dwarf orbiting a main sequence star. Nova Reticulum 2020 has been briefly visible from the Southern Hemisphere.

    1
    A nova is a star that suddenly pops into view. Early stargazers thought they were new stars. Today, we know differently. Image via Ernesto Guido (@comets77 on Twitter).

    Veteran comet hunter Robert McNaught from Coonabarabran, Australia, must have been perplexed – and then surprised – and then delighted when he noticed something peculiar on CCD images of the night sky, taken July 15, 2020. It was a faint, but visible star where none had appeared before. Such a star is called a nova, from a Latin word meaning new. This one is in front of the southern constellation Reticulum. Once confirmed by other astronomers, and reported in The Astronomer’s Telegram on July 16, the object was quickly announced to the world’s community of variable star observers as Nova Reticuli 2020 (N Ret 2020).

    It’s a rare find: a nova visible to the eye!

    2
    Nova Reticulum 2020, via Comets & Asteroids.

    Astronomers have determined that this outburst is of the sort called a classical nova. That is, it’s created in a double-star system where one star is a white dwarf and the other is an ordinary main sequence star, not dissimilar from our sun. These two stars are close together in space, orbiting one another on a timescale of only hours. Because they’re close – and because the white dwarf is a collapsed object with very powerful gravity (a teaspoon of white dwarf material would weigh several tons) – hydrogen from the main sequence star is drawn into an accretion disk around the white dwarf. Eventually, this hydrogen piles onto the surface of the white dwarf. As explained on the website Cosmos from Swinburne University:

    “As more hydrogen (and helium) is accreted, the pressure and temperature at the bottom of this surface layer increase until sufficient to trigger nuclear fusion reactions [the same process that causes our sun and most other stars to shine]. These reactions rapidly convert the hydrogen into heavier elements creating a runaway thermonuclear reaction where the energy released by the hydrogen burning increases the temperature, In a classical nova, a dense white dwarf pulls material from a companion star. The material piles up on the white dwarf’s surface until thermonuclear processes begin, creating an outburst. Image via NASA/ JPL-Caltech.which in turn drives up the rate of hydrogen burning.

    The energy released through this process ejects the majority of the unburnt hydrogen from the surface of the star in a shell of material moving at speeds of up to 1,500 km/s. This produces a bright but short-lived burst of light – the nova.”

    A classical nova outburst can occur again and again in a system of this kind.

    Nova Reticulum 2020 is associated with a known object in the database of the American Association of Variable Star Observers, labeled MGAB-V207 and categorized as a cataclysmic variable star. These sorts of stars are known to undergo classical nova outbursts due to mass transfer between a main sequence star and a white dwarf.

    3
    In a classical nova, a dense white dwarf pulls material from a companion star. The material piles up on the white dwarf’s surface until thermonuclear processes begin, creating an outburst. Image via NASA/ JPL-Caltech.

    Can you see Nova Reticuli 2020? Possibly, if it hasn’t faded yet, and if you live in the Southern Hemisphere, where the constellation Reticulum can be seen. On July 17, writing at Astronomy.com, Alison Klesman said Nova Reticuli 2020 was shining at around magnitude 5.

    That is, it’s visible to the eye, but only barely.

    If it’s still visible to the eye, you will need a very dark to see the nova. If you have that – and a constellation chart to show you how to find Reticulum – look first for the bright stars Alpha and Gamma Doradus, shown on the chart below (apologies for the blurriness of the chart; be sure to view it larger)

    Good luck!

    4
    View larger. | If you live in the Southern Hemipshere, you can see the constellation Reticulum and the nova. You can pinpoint Nova Reticuli 2020 by looking roughly 5 degrees west of magnitude 3.3 Alpha Doradus and 4.25 degrees southwest of magnitude 4.3 Gamma Doradus. Notice that these 2 stars make a triangle with the nova. If the nova has gotten fainter, try using binoculars to bring it into view. Image via Alison Klesman/ Astronomy.com.

    5
    Congratulations to comet hunter Robert McNaught, who was the first to spot Nova Reticuli 2020! Image via Abc.net.au.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.orgin 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 8:48 am on July 10, 2020 Permalink | Reply
    Tags: "How volcanoes explode deep under the ocean", , , EarthSky, ,   

    From EarthSky: “How volcanoes explode deep under the ocean” 

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    From EarthSky

    July 8, 2020
    Eleanor Imster

    Explosive volcanic eruptions are possible deep down in the sea – although the water masses exert enormous pressure there. An international team reports how this can happen.

    1
    An island of the Azores: It’s an example of an underwater volcano that has reached the sea surface. The crater is clearly visible. Image via aroxopt/ iStock.com/ University of Würzburg.

    Most of the volcanic eruptions on Earth happen unseen at the bottom of the world’s oceans. In recent years, oceanography has shown that these submarine volcanoes not only deposit lava, but also eject large amounts of volcanic ash.

    Bernd Zimanowski, of Julius-Maximilians-Universität in Bavaria, said in a statement:

    “So even under layers of water kilometers thick, which exert great pressure and thus prevent effective degassing, there must be mechanisms that lead to an ‘explosive’ disintegration of magma.”

    How are explosive volcanic eruptions possible deep underwater? Zimanowski is part of an international research group that has now demonstrated a mechanism for these undersea explosions. The results were published June 29, 2020, in the peer-reviewed journal Nature Geoscience.

    2
    There are around 1,900 active volcanoes on land or as islands. The number of submarine volcanoes is estimated to be much higher. Exact numbers are not known because the deep sea is largely unexplored. Accordingly, most submarine volcanic eruptions go unnoticed. Submarine volcanoes grow slowly upwards by recurring eruptions. When they reach the water surface, they become volcanic islands – like Stromboli near Sicily (an active volcano, pictured above) or some of the Canary Islands. Image via Novinite.com.

    The team did research at the Havre Seamount volcano , which lies northwest of New Zealand about half a mile (1,000 meters) below the sea surface. The scientific community became aware of the volcano when it erupted in 2012. The eruption created a floating carpet of pumice that expanded to about 150 square miles (400 square km), roughly the size of the city of Vienna.

    For the new research, the team used a diving robot to examine the ash deposits on the seabed. From the observational data the group detected more than 100 million cubic meters (3.5 billion cubic feet) of volcanic ash. The diving robot also took samples from the seafloor, which were then analyzed in the lab. Zimanowski said:

    “We melted the material and brought it into contact with water under various conditions. Under certain conditions, explosive reactions occurred which led to the formation of artificial volcanic ash.”

    The comparison of this ash with the natural samples showed that processes in the laboratory must have been similar to those that took place at a depth of 1,000 meters on the sea floor. Zimanowski added:

    “In the process, the molten material was placed under a layer of water in a crucible with a diameter of ten centimeters and then deformed with an intensity that can also be expected when magma emerges from the sea floor. Cracks are formed and water shoots abruptly into the vacuum created. The water then expands explosively. Finally, particles and water are ejected explosively. We lead them through an U-shaped tube into a water basin to simulate the cooling situation under water.”

    The particles created in this way, the “artificial volcanic ash”, corresponded in shape, size and composition to the natural ash.

    The researchers believe that further investigations should also show whether underwater volcanic explosions could possibly have an effect on the climate. Zimanowski said:

    “With submarine lava eruptions, it takes a quite long time for the heat of the lava to be transferred to the water. In explosive eruptions, however, the magma is broken up into tiny particles. This may create heat pulses so strong that the thermal equilibrium currents in the oceans are disrupted locally or even globally.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 7:41 am on July 1, 2020 Permalink | Reply
    Tags: "How dust could make some exoplanets more habitable", , , , , EarthSky,   

    From EarthSky: “How dust could make some exoplanets more habitable” 

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    From EarthSky

    July 1, 2020
    Paul Scott Anderson

    A new study from scientists in the UK suggests that atmospheric dust could increase the habitability of some exoplanets, especially those orbiting red dwarf stars.

    1
    Three computer simulations depicting how airborne dust can be distributed by winds on rocky exoplanets like Earth. Image via Denis Sergeev/ University of Exeter/ ScienceAlert.

    What makes a planet habitable? Various factors can affect a planet’s ability to sustain life, such as temperature, amount of water, composition of both the planet and its atmosphere and the amount of radiation from the host star. Last month, researchers in the U.K. said they’ve found that a common component of atmospheres – dust – could increase the habitability of some exoplanets.

    The peer-reviewed results were published in Nature Communications on June 9, 2020.

    Researchers from the University of Exeter, the Met Office and the University of East Anglia (UEA) were involved in the new study.

    2
    Effects of dust on the climate of planets. For a tidally locked planet (a) and non-tidally locked planet (b), panels a–d show the base state of the planets, e–h show the short- (stellar) and long-wave (infra-red) forcing (change in surface energy balance) introduced by dust and i–j show the resultant effect of the forcing on the surface temperature. Blue arrows show the motion of the planet around the star, and green arrows show the rotation of the planet relative to the star. Image via Boutle et al./ Nature Communications.

    From the paper:

    “Identification of habitable planets beyond our solar system is a key goal of current and future space missions. Yet habitability depends not only on the stellar irradiance, but equally on constituent parts of the planetary atmosphere. Here we show, for the first time, that radiatively active mineral dust will have a significant impact on the habitability of Earth-like exoplanets.”

    In our own solar system, Mars typically comes to mind when we think of a dusty world, yet it remains a cold, dry planet on the surface due to its very thin atmosphere. But for some exoplanets, especially those that are tidally locked to their stars, it could be a different situation. Ian Boutle, from both the Met Office and University of Exeter and lead author of the study, said in a statement:

    “On Earth and Mars, dust storms have both cooling and warming effects on the surface, with the cooling effect typically winning out. But these ‘synchronised orbit’ planets are very different. Here, the dark sides of these planets are in perpetual night, and the warming effect wins out, whereas on the dayside, the cooling effect wins out. The effect is to moderate the temperature extremes, thus making the planet more habitable.”

    The dust factor is especially significant for planets orbiting red dwarf stars, the most common type of star in our galaxy. Many planets around those stars are likely to be tidally locked, orbiting with one side of the planet always facing the star, just as the moon always keeps one side facing Earth. Those planets would have one side always in daylight, and the other always in darkness. If there is a lot of dust, that could help cool down the hotter day side, and warm the colder night side.

    3
    Artist’s concept of a cloudy and rocky exoplanet orbiting a red dwarf star. Dust in the atmospheres of planets like this could moderate the temperature extremes if the planets are tidally locked, helping to make them more habitable. Image via L. Hustak/ J. Olmsted (STScI)/ NASA.

    In an interesting scenario, dust could help hot planets retain their surface water, if they have any. A planet that is really hot, like Venus, could be cooled down by enough dust in the atmosphere. The amount of dust would then increase as water starts to be lost on the planet’s surface, which, ironically, in a process called negative climate feedback, would then slow down the loss of water. From the paper:

    “On tidally-locked planets, dust cools the day-side and warms the night-side, significantly widening the habitable zone. Independent of orbital configuration, we suggest that airborne dust can postpone planetary water loss at the inner edge of the habitable zone, through a feedback involving decreasing ocean coverage and increased dust loading.”

    The amount of energy a planet receives from its star is an important part of assessing habitability, but as Manoj Joshi from UEA noted, the composition of the atmosphere, including dust, is also very important:

    “Airborne dust is something that might keep planets habitable, but also obscures our ability to find signs of life on these planets. These effects need to be considered in future research.”

    The researchers performed a series of simulations of rocky Earth-sized planets and found that naturally occurring mineral dust can have a big impact on the habitability of such planets.

    4
    Mars is a very dusty place, and massive dust storms are common, but the dust doesn’t warm the planet much since the atmosphere is so thin. Image via SA/ Roscosmos/ CaSSIS/ CC BY-SA 3.0 IGO/ New Scientist.

    Duncan Lyster, who ran an undergraduate experiment as part of the overall study (and now builds his own surfboards), also said:

    “It’s exciting to see the results of the practical research in my final year of study paying off. I was working on a fascinating exoplanet atmosphere simulation project, and was lucky enough to be part of a group who could take it on to the level of world-class research.”

    The researchers also point out that dust in a planet’s atmosphere must be taken into account when searching for possible biomarkers in that atmosphere. Those biomarkers could include gases such as oxygen, methane and ozone, and if there also was enough dust, the dust could obscure the detection of them, producing a false negative result. If potential biomarkers were missed in that way, the planet might be erroneously characterized as uninhabitable. Such biomarkers, which will be searched for with upcoming space telescopes like the James Webb Space Telescope (JWST) and others, will be a crucial aspect of the search for evidence of life beyond our solar system. Identifying them is already a challenge due to the extreme distances to these worlds, so knowing the amount of dust in a planetary atmosphere will be important as well. From the paper:

    “The inclusion of dust significantly obscures key biomarker gases (e.g. ozone, methane) in simulated transmission spectra, implying an important influence on the interpretation of observations. We demonstrate that future observational and theoretical studies of terrestrial exoplanets must consider the effect of dust.”

    Nathan Mayne from the University of Exeter, who assisted with the study, also noted how astrophysics in general will play a large role. He said:

    “Research such as this is only possible by crossing disciplines and combing the excellent understanding and techniques developed to study our own planet’s climate, with cutting edge astrophysics. To be able to involve undergraduate physics students in this, and other projects, also provides an excellent opportunity for those studying with us to directly develop the skills needed in such technical and collaborative projects. With game-changing facilities such as the JWST and E-ELT, becoming available in the near future, and set to provide a huge leap forward in the study of exoplanets, now is a great time to study physics!”

    NASA/ESA/CSA Webb Telescope annotated

    ESO/E-ELT, 39 meter telescope to be on top of Cerro Armazones in the Atacama Desert of northern Chile. located at the summit of the mountain at an altitude of 3,060 metres (10,040 ft).

    The new assessment regarding exoplanetary dust will be very beneficial to scientists who will be looking for biomarkers and other evidence for habitable exoworlds, as well as studying how dust can affect a planet’s climate and environment overall.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
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