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Space Science

Exoplanet Has Showers of Pebbles 341

Posted by CmdrTaco
from the gonna-need-a-thicker-umbrella dept.
mmmscience writes "The newly-discovered exoplanet COROT-7b has an unusual form of precipitation: rocks. Because it orbits so close to its sun, the temperature on its sun-facing side is around 4220 degrees Fahrenheit. That's hot enough for rocks to vaporize — not unlike water evaporating on Earth. And, like Earth, when the vapor cools in the upper atmosphere, it forms clouds and begins to rain. But instead of water, COROT-7b gets a shower of pebbles."
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Exoplanet Has Showers of Pebbles

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  • Wow (Score:5, Funny)

    by clone53421 (1310749) on Thursday October 01, 2009 @11:42AM (#29606575) Journal

    That's pretty cool, in a geeky sort of way.

    I wish I could see it... but I don't think the environment would be terribly friendly to my sensitive skin.

    • Re:Wow (Score:5, Funny)

      by geoffrobinson (109879) on Thursday October 01, 2009 @12:00PM (#29606847) Homepage

      Yeah, I'm part Irish too. I can't stand being in the Sun/insert favorite star here.

    • I wish I could see it... but I don't think the environment would be terribly friendly to my sensitive skin.

      Just put on an extra thick layer of sunscreen and you should be fine.
      • Re:Wow (Score:5, Interesting)

        by Rei (128717) on Thursday October 01, 2009 @01:20PM (#29607953) Homepage

        The planet is tidally locked. Just stay on the dark side of the planet. The equilibrium temperature there is 59F [wustl.edu] -- not bad at all.

        One thing that occurs to me is that if the mass transfer rate is as high as they're suggesting -- and I have no reason to suspect otherwise -- it seems to me that this planet would be *highly* tectonically active. Unlike rain, which just runs off, the pebbles will stick around where they fall. This means that the crust will have a lot of weight bearing down on it on the cold side, sinking into the mantle and likely leading to heavy volcanism and tectonic activity. And the erosion of the hot side should lead to an upwelling of exposed mantle material as the planet tries to relax into a sphere.

        The awesome thing is, with such a reasonable temperature on the cool side, it could actually be habitable to LAWKI -- except for that likely lack of water thing, (unless there's been heavy cometary activity since the planet became tidally locked).

        This planet must have an incredible range of minerals, way unlike anything on Earth -- the star basically mining the crust and even mantle on one side and depositing it after chemical vapor deposition onto the other side. If we ever go interstellar as a species, I wouldn't be surprised to see heavy mining activity on planets like that.

        • Oops (Score:5, Informative)

          by justthinkit (954982) <floyd@just-think-it.com> on Thursday October 01, 2009 @01:28PM (#29608043) Homepage Journal
          The planet is tidally locked. Just stay on the dark side of the planet. The equilibrium temperature there is 59F -- not bad at all.

          This star-facing side has a temperature of about 2600 degrees Kelvin (4220 degrees Fahrenheit). That's infernally hothot enough to vaporize rocks. The global average temperature of Earth's surface, in contrast, is only about 288 degrees Kelvin (59 degrees Fahrenheit).

      • Re:Wow (Score:5, Interesting)

        by Rei (128717) on Thursday October 01, 2009 @01:31PM (#29608081) Homepage

        Oh, and sweet -- Some more highlights after further reading:

        "Sodium, potassium, silicon monoxide and then oxygen -- either atomic or molecular oxygen -- make up most of the atmosphere." But there are also smaller amounts of the other elements found in silicate rock, such as magnesium, aluminum, calcium and iron. ... As you go higher the atmosphere gets cooler and eventually you get saturated with different types of 'rock' the way you get saturated with water in the atmosphere of Earth ... Elemental sodium and potassium, which have very low boiling points in comparison with rocks, do not rain out but would instead stay in the atmosphere, where they would form high gas clouds buffeted by the stellar wind from COROT-7.

        So... the only one of those things that will be a gas at the surface on the far side is oxygen. The article says the atmosphere may not be breathable, but I have to wonder... why not?

        Also, in the case what what condenses in the atmosphere is crystaline (I don't see anywhere which suggests whether they would be or not -- it all depends on how fast it cools), look at the list of the raining minerals:

        enstatite, corundum, spinel, and wollastonite.

        Enstatite can be a gemstone. Crystals of corundum are otherwise known as ruby and sapphire. There are many types of spinels, a number of whose crystals are considered gemstones. Etc. So *if* what condenses is crystalline, it could literally be raining gems on that planet.

        • Re: (Score:3, Insightful)

          by jamstar7 (694492)

          So... the only one of those things that will be a gas at the surface on the far side is oxygen. The article says the atmosphere may not be breathable, but I have to wonder... why not?

          Metals poisoning, I'm thinking. When was the last time you tried to breathe some iron?

          • Re: (Score:3, Insightful)

            by Gerzel (240421) *

            Or ultra fine crystal shards and glass...lots and lots of dust I think would get your lungs long before the metals would poison your lungs.

    • You could just turn up the air conditioner. Of course, then if it gets too cold, you can crank up the heater. And if the heater's too strong, you could crank up the AC. Then maybe make some icy margaritas. Just don't hit the "fuel guzzler" and make pop-tarts at the same time!

    • Re: (Score:3, Funny)

      by FatdogHaiku (978357)

      That's pretty cool, in a geeky sort of way.

      I wish I could see it... but I don't think the environment would be terribly friendly to my sensitive skin.

      Break out the SPF 15000000 and put it on with a trowel.

  • Not unusual (Score:5, Funny)

    by BadAnalogyGuy (945258) <BadAnalogyGuy@gmail.com> on Thursday October 01, 2009 @11:42AM (#29606579)

    We get solid precipitation here on earth all the time.

    Sometimes it's hail, sometimes sleet.

    The best is frogs, though.

    • Re:Not unusual (Score:5, Insightful)

      by Thelasko (1196535) on Thursday October 01, 2009 @11:44AM (#29606625) Journal

      We get solid precipitation here on earth all the time.

      The parent raises a good point. How do we know the rock comes back down to the surface as a solid? Why doesn't it rain lava?

      • by FudRucker (866063)
        at what temperature does lava solidify?, figure that out and i bet you will have your answer.
      • Re:Not unusual (Score:5, Informative)

        by Chris Burke (6130) on Thursday October 01, 2009 @12:30PM (#29607225) Homepage

        The parent raises a good point. How do we know the rock comes back down to the surface as a solid? Why doesn't it rain lava?

        I'm going to make an educated guess, and say it's in the same way we "know" that it rains any kind of rock at all -- because that's what the simulations said. It says they even varied constraints based on not knowing exactly what the composition of the planet is, but they kept ending up with the same basic result.

        So it all comes down to how good the simulation model is. It's possible it's inaccurate in a way that it is right that there is rock-based precipitation, but that it's in liquid form, but I certainly have no idea.

        • Re:Not unusual (Score:5, Interesting)

          by fireslack (1039158) <fireslack@gmail.com> on Thursday October 01, 2009 @01:54PM (#29608445) Journal
          Am I the only one who is deeply impressed that we even KNOW a planet is there? It is difficult to observe Mercury because of its proximity to the sun, but we can see a planet that is 1.7 Earth radii, 42 light years away, and is so close to its parent star, it has an orbital period of 20 hours. Hours! That means it is insanely close to its star. Solid rock or lava be damned. How about a pat on the back for finding any exoplanets at all?
          • Re: (Score:3, Insightful)

            by dargaud (518470)
            It's probably because it passes in front of its sun at every orbit, and we can see the noticeable difference in luminosity. Mercury rarely goes in front of the sun and the luminosity difference is in the epsilon range.
      • by MarkRose (820682)

        This calls for... a song!

        Give me that Liquid Lava Love, Just can't get enough
        Slow like honey, oh so foamy, I like your flow
        Liquid lava love, you make me erupt
        Overflowing, don't cha know I'm 'bout to explode

        Girl you got my fire burning, body yearning
        Can't take it no more, can't take it no more
        Rain is falling, why you staling
        I can't take it no more, can't take it no more
        This volcano's ready to blow
        So just lay back and take it and let it go
        Let your liquid lava flow...

        Somehow I don't think Keven Michael was thi

    • The best is frogs, though.

      Yeah, but frogs are mostly liquid (rigid bags of water just like us).

      I mean, there's a reason it's called "a rain of frogs" not a "blizzard of frogs" or a "hailstorm of frogs".

      That said, my actual favorite is when it rains fish.

    • Re: (Score:3, Interesting)

      by QuoteMstr (55051)

      Absolutely right. What we consider liquid and solid depends on our local environment. In the outer planets of our solar system, water is a rock. It behaves just like rocks here on Earth do: it faults tectonically, crystallizes in various forms, and differentiates into crust, mantle, and core. These bodies have "hydro-"logical cycles made up of methane, which is normally a gas for us.

      It's not unusual at all for something we consider to a be a "rock" actually form the hydrological cycle for a much warmer body

  • by gblackwo (1087063)
    Neato
  • Summary inaccurate (Score:3, Insightful)

    by JoshuaZ (1134087) on Thursday October 01, 2009 @11:43AM (#29606595) Homepage
    This is a hypothesized event. The evidence for it is slim based primarily on modeling. While this is really cool if correct, one needs to understand that this isn't by any means a slam dunk.
    • by clone53421 (1310749) on Thursday October 01, 2009 @11:46AM (#29606643) Journal

      True. Also, I'm wondering if "pebbles" is an appropriate description of the condensed rock or if it wouldn't be more aptly described as "sand" or even "dust". Raindrops stick together; depending on how quickly the rock condenses, it might not have time to grow very large. (Then again, it could grow like hail, if the rock was in the liquid state for any significant amount of time.)

      • Re: (Score:3, Funny)

        Yeah. "Pebbles" is probably inaccurate. I find it hard to believe the hypothesis that there are storms on this planet where redheaded female pre-historic babies with pony tails fall out of the sky.

    • by Sockatume (732728) on Thursday October 01, 2009 @11:50AM (#29606719)

      To be fair, the original press release also mangles observed and simulated results like crazy. They've definitely found the exoplanet and determined its orbit and mass. They've either confirmed or hypothesised from simulation that there are no volatile compounds on or around the planet, which they hypothesise is due to bake-out. They've hypothesised based on simulations that it is likely to have a rock-based atmosphere which, depending on composition, could be verified spectroscopically.

    • Re: (Score:3, Informative)

      by Thanshin (1188877)

      While this is really cool if correct, one needs to understand that this isn't by any means a slam dunk.

      Well, it does come quite close to being a "slam dunk".

  • Flintstones (Score:3, Insightful)

    by SirLoadALot (991302) on Thursday October 01, 2009 @11:43AM (#29606601)

    This is just like on the Flintstones, where everything is made out of stone -- because it's the Stone Age, silly! Further research will reveal the pterodactyl airplanes, I'm sure.

  • by slashmatteo (1606315) on Thursday October 01, 2009 @11:44AM (#29606621)
    "the temperature on its sun-facing side is around 4220 degrees Fahrenheit." For anyone using the SI, this is about 2327 degrees Celsius
  • US Fidelis is setting up its new headquarters here for all the car warranty repairs they'll get from the new space colony there.
  • Rock Rainbows? (Score:5, Interesting)

    by MarkRose (820682) on Thursday October 01, 2009 @11:49AM (#29606703) Homepage

    Given that different material will have different melting temperatures, that should lead to the different metals coalescing at different heights. At sunset, there ought to be a layering affect as the last rocks fall back to the surface, a rock rainbow in effect. Of course, it probably won't last long with the whole planet being molten.

  • Having parked under a tree during a hailstorm, how is this different from something as solid as hail raining down on you?

    Ice is pretty solid and it's created by pretty much the same phenomenon as the pebbles in this planet. All you need is a temperature range between solid to gas of a substance and a rotation speed slow enough to cool the other side by radiation.

    But I'm not going to shout down any scientist who's spent enough time to measure the spectra, do the math about temperatures and conclude this

  • by tomhudson (43916) <.barbara.hudson. ... bara-hudson.com.> on Thursday October 01, 2009 @11:51AM (#29606725) Journal

    Teacher: Why are you late?
    Student 1: I was throwing pebbles in the pond.
    Teacher: (to student #2) Why are you late?
    Student 2: I was throwing pebbles in the pond.
    Teacher: (to student #3) Let me guess - you were throwing pebbles in the pond too?
    Student 3: I'm Pebbles.

    • Re: (Score:2, Funny)

      by jlintern (1169449)
      Teacher: Why are you late? Student 1: I was on top of Cherry Hill. Teacher: (to student #2) Why are you late? Student 2: I was on top of Cherry Hill. Teacher: (to student #3) Let me guess - you were on Cherry Hill too? Student 3: I'm Cherry.
  • by Chris Burke (6130) on Thursday October 01, 2009 @11:52AM (#29606735) Homepage

    It is nearly impossible to imagine a deluge of pebbles falling from the sky, or turning on the morning forecast to hear reports of "rocking" instead of "raining."

    Oh I can imagine it. You see dark clouds roll in, crowding around. In the distance but growing louder, the rapid heavy percussion of the rock shower begins. Then in the cloud at the front, you see a flash of light and a shower of sparks like a pyrotechnic burst. Seconds later, instead of a crash of thunder, you hear the wail of an electric guitar.

    It is now rocking. Rocking hard core.

    This is the awesomest planet ever.

    • by Jeng (926980)

      Dethklok needs to record their next record there.

      • by Chris Burke (6130)

        Heh, I can imagine Nathan Explosion's voice after he reads the article.

        "We have to record our next album there. It's the most brutal planet ever."

        And of course they'd inexplicably have an enormous interstellar spaceship shaped like a Viking ship and covered in spikes.

  • Having read TFA, I am interested why the authors hypothesise that the precipitation is as solid rocks. Intuitively, it would make more sense that it would be in a liquid phase (while I have no idea of what pressures would exist on the planet, and am no geologist, liquid rocks seem to exist across temperature ranges in excess of 100's of degrees here on earth.) Admittedly, the article does seems to imply that there is no rotation of the planet, and thus gaseous rock migrating to the super-cold side might (
    • Re: (Score:3, Interesting)

      by Shotgun (30919)

      I would expect that the elements/molecules with higher melting points would migrate to the sunward side, while more volatile stuff would end up in the shadows. Would you have something like a "shield" of aluminum oxide guarding an ocean of iron?

    • by radtea (464814)

      n fact, would this imply that there is a large scale migration of rock from the sunward side of the planet to that opposed to the sun (and would this in turn alter the fundamental planet shape? I envisage dinnerplate planets...)

      I briefly entertained the same fantasy--I even wondered if this could destablize the tidal locking by transporting mass from the point closest to the sun to more distant points, which on reflection seems highly unlikely.

      It is possible that the processes described in the article resul

    • Re: (Score:3, Interesting)

      Unless the planet is very small, no matter where or how you move material around, it's going to return to a roughly spherical shape, regardless. In fact, a big part of the definition of "planet" is some mass large enough that gravity forces it into a sphere.

      Now, you could imagine a planet where this front-to-back migration actually stirs the planet. That would be cool.

  • by emurphy42 (631808) on Thursday October 01, 2009 @11:55AM (#29606785) Homepage
    ROCKS FALL! EVERYONE DIES!
  • Fallout (Score:5, Interesting)

    by mbone (558574) on Thursday October 01, 2009 @11:56AM (#29606805)

    That has happened on Earth too. We call it Fallout.

    I am not kidding. A surface nuclear burst in the megaton range will vaporize millions of tons of rock and soil. This material will cool, condense, and and fall as
    little pebbles or hail. In this case, it's radioactive, but otherwise the physics is the same.

    • Re:Fallout (Score:5, Interesting)

      by mk_is_here (912747) on Thursday October 01, 2009 @12:06PM (#29606943)

      To enjoy a natural one, without the radioactive waste, all you need is a volcano eruption.

    • Let's not exaggerate (Score:5, Informative)

      by slyborg (524607) on Thursday October 01, 2009 @12:23PM (#29607105)

      Some hyperbole here.

      The Castle Bravo test shot (http://en.wikipedia.org/wiki/Castle_Bravo) was one of the largest thermonuclear detonations ever, with an estimated yield of 15-22 MT. The blast crater from Bravo was 2000m in diameter and 75m deep. Assuming it was square because I'm too lazy for math today, that's about 300,000 cubic meters. Assuming that this was blasted in solid granite (http://www.allmeasures.com/Formulae/static/materials/32/density.htm) you get about 780k metric tons.

      However, most of this material wasn't vaporized, it was pulverized by the shock wave and propelled as a solid into the mushroom cloud. The actual quantity of material melted I wouldn't hazard to estimate, but it was a small proportion of the overall material excavated.

      Much as in the "it's raining rocks!" planet, this precipitation would be much closer in form to dust, not "pebbles". One of the reason that water on earth comes in larger forms is that the water molecule has a charge, and will aggregate electrostatically. I don't think that would be true of this silicate cloud.

      • by Sockatume (732728) on Thursday October 01, 2009 @01:41PM (#29608255)

        Actually a 75m section of a 2000m cylinder, from pi * r^2 * depth comes out at about 200 MILLION cubic metres. Multiply that by about two metric tonnes per cubic metre (sandstone) and you get four hundred million metric tonnes. I can't be bothered to account for the curvature of the crater, but I doubt it'll bring that down much under a hundred million tonnes. There's still the "vapourisation versus excavation" question, of course, I'm just pointing out that your estimate of mass is off by three orders of magnitude.

      • Re: (Score:3, Interesting)

        by Sockatume (732728)

        From underground nuclear tests, the "melt cavity" created by vaporization of rock and the flow of liquefied rock is about 2000 cubic metres per kiloton, so the OP's estimate is about right, assuming one half of the energy is lost to the air by a surface explosion.

  • by JohnHegarty (453016) on Thursday October 01, 2009 @12:05PM (#29606919) Homepage

    Meanwhile on COROT-7b scientists find a new planet so cold that water would actually create "oceans" on the surface , and even freeze at the poles.

    They laugh at the though ever existing on that planet.

  • by gpronger (1142181) on Thursday October 01, 2009 @12:07PM (#29606953) Journal
    My first reaction was that this (assuming the theory is correct) is about as cool of a discovery - concept I've read about in a long time. At the same time it brings to point a thought that one of the problems with popular Sci-Fi is that it misses on potential of "stuff" "out-there" (space) being wilder and different (including life) than we've yet to imagine.

    If you consider the variety of habitats that we find life in our tiny part of the cosmos (Earth) and that life keeps being discovered in more and bizarre places (by human standards) when you extrapolate that out, I tend to think it may be literally beyond our imagination.

    If we, by whatever means, met intelligent life, would we be able to communicate; sure math is universal, but consider the issues communicating ideas and values across cultures when its the same species. Consider a collective consciousness, what does the term "I" or "me" mean to it (them).
  • Really? (Score:3, Insightful)

    by swanzilla (1458281) on Thursday October 01, 2009 @12:07PM (#29606959) Homepage
    FTA:

    It is nearly impossible to imagine a deluge of pebbles falling from the sky, or turning on the morning forecast to hear reports of âoerockingâ instead of âoeraining.â

    Does this seem difficult to imagine, let alone nearly impossible?
    Imagine, if you can, something somewhere else very similar to something standard here!

  • by SloWave (52801) on Thursday October 01, 2009 @12:16PM (#29607045) Journal

    I'm sure the methane based party animals on Titan also point to Earth and oooh and aaah about how solid H2O actually melts, vaporizes, and falls from the sky as rain, hail, and snow under the tremendous heat we have here.

  • Minerals melt and boil at various temperatures and at 2,370 C most minerals will probably break down into smaller molecules and atoms. Since Silicon dioxide (quartz) is a stable and common component of various kinds of rocks, and it has a boiling point of 2,230 C, I suspect that the surface is a sea of melted and boiling quartz and that most of the "atmosphere" is gaseous quarts, and that the "rain" is droplets of liquid quartz. Aluminum oxide melts at 2072C and boils at 2,980C, so the "ocean" is probab

  • by wiredog (43288) on Thursday October 01, 2009 @12:40PM (#29607373) Journal

    ow!

  • by Anonymous Coward on Thursday October 01, 2009 @12:42PM (#29607387)
  • by polishphorce (1648015) on Thursday October 01, 2009 @12:44PM (#29607415)
    ...and if you like pina coladas and getting bludgeoned in the rain...
  • Conveyor-belt planet (Score:5, Interesting)

    by FriendlyPrimate (461389) on Thursday October 01, 2009 @12:46PM (#29607453)
    What I find interesting about this planet is that it's tidally locked with it's star, so one side is over 4000F, while the other is -370F. That could imply that the surface continuously evaporates on the hot side and condenses out of the atmosphere on the cold side. So the planet is essentially a conveyor belt always in the process of being destroyed and created. The contents of the entire planet could have gone through this process many times already.
    • by FriendlyPrimate (461389) on Thursday October 01, 2009 @01:40PM (#29608245)
      BTW....this is related to the process that is thought to occur on most tidally-locked rocky planets. They likely do not have atmospheres, since it entirely sublimates on to the cold side of the planet. When the atmosphere freezes out on the cold side, it reduces the atmospheric pressure on the cold side, which causes the atmosphere on the hot side to flow to the cold side, repeating the process until the entire atmosphere is gone. But in this particular case, the 'atmosphere' is getting continuously replaced through evaporation of the planet itself. This process is also one of the reasons why planets around red dwarf stars may be unlikely, since the planet has to be close to the star to receive enough energy from it, but being that close to the star increases the likely-hood of it becoming tidally locked with the star.

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