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Space

Planets In The Habitable Zone 208

Posted by timothy from the it's-always-the-primates dept.
mistah_monkey writes: "The BBC reports that an international team of scientists have identified some planets in what they call the habitable zone. Apparently, the planets may be as big as Jupiter, but exist in a region surrounding the stars they orbit in which water can exist as a liquid, which is good news for those of us who believe that little green men might actually be out there somewhere."
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Planets In The Habitable Zone More

Planets In The Habitable Zone

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  • Re:hmm.. (Score:1)

    by Anonymous Coward
    > 4.3633 * 10^14 m/s.

    um, isn't light 2.99792458 * 10^8

    does anyone else see a problem with this??
  • I think it's beyond our capabilities to say with certainty that life must have a necessity for oxygen, water and other things that most life on our planet depends on. We now know that there is life in places we once thought absolutely impossible, such as the volcanic vents under the ocean where the temperature and volitility should eliminate any chance for life -- but there it is.

    I would assert that the chances of life everywhere in the universe being relatively paralell to our own on this planet (humanoid, mamallian, reptilian, etc) or life being radically different in form and survival throughout are about equal. With only our own planet as a base for the time being, it is difficult to establish accurate foresight.
    ---
    seumas.com

  • The Internet is designed as a communications medium, so putting one's contact information on-line seems to me to be a logical thing to do, much like listing one's phone number in Real Life. Do you think that listing one's phone number is "just asking for abuse"? I, personally, am on the net because I *want* people to be able to get a hold of me, by phone or fax or email or instant message. If I don't want to be bothered, I can do what I do in real life, and yank my network connection for a while.

    You have not thought this through.


    Rev. Dr. Xenophon Fenderson, the Carbon(d)ated, KSC, DEATH, SubGenius, mhm21x16
  • Density is matter per unit volume. Gravity depends on the amount of mass. Jupiter, a very massive but not very dense planet has significant atmosphere. In fact, that's all it is - like the Solar System's best restaurant, it's all ambiance.

    Ceres is, per unit volume, quite a bit more dense than Jupiter - but it has many fewer units of volume until all it's mass is accounted for. So it is much less massive than Jupiter, and therefore has a much lesser gravity - hence no ability to retain an atmosphere.

    It is the gravity of a body than keeps it's gravity from floating off into space, not it's density. Density can only be viewed as playing a role when the two bodies are of similar volume, at which point a greater density is a sign of greater mass - not vice versa.

    To put it another way, density and gravity both depend on mass. Density also depends on volume within which the mass is contained.

    I'm not sure of the accuracy of the following (maybe an astronomy geek can back me up) but if you were to take the mass of the Earth, and distribute it over ten thousand times the volume - making a nebula - it would be just as able to retain it's atmosphere as it is now.

    The REAL jabber has the /. user id: 13196

  • Using space and ground-based telescopes, I should think it would be possible to look for "artifacts", evidence of technology. As an example, how about searching for the flares produced by Bussard ram-jet drives? These should be visible for hundreds of lightyears, at least. Also, look for cosmic anomalies that might point to massive engineering projects by highly advanced civilizations, such as Dyson Spheres, "ringworlds" (a la Niven), etc.
  • You mean, like Europa and Titan, moons of gas giants in our own solar system that are capable of supporting life?

    And you mean "tides" as opposed to "tidal wasves(sp?)", correct? Tidal forces on a moon of a gas giant would be very impressive, to say the least.
  • Okay, not war. How 'bout overconsumption? It has certainly ended numerous civilizations here on Earth, and no one is even sure if the six billion we hope to support right now is a sustainable population long-term.

    And the thing that makes it a much better curtain-closer than war is that we will sit around and watch it happen and be unwilling or unable to change our way of life enough to stop it. Witness global warming.
  • The paper only talks about two planets, not the three referred to in the BBC article. The first one mentioned has a "year" of only a few Earth days, which the paper calls "51 Peg"-like, alluding to one of the first planets detected, and the class of extra-solar planets named after it. The second star is a brown dwarf candidate with a mass between 46 and 190 times that of Jupiter. I see no mention whatsoever of the really exciting third planet which supposedly has a period of a little over one Earth year, orbiting a Sun-like star. The most exciting possibility is not that liquid water would exist on the gas giant (it can't), but that it might have terrestial moons at a habitable temperature. Empirically, moons have been observed to have volcanic activity (Io) as well as atmospheres (Titan), which could pave the way for life to come into being.

    The article does bring up the interesting point that the "51 Peg"-like stars are ideal candidates to be observed during a transition (like an eclipse, the planet is temporarily between us and the star in a transition). However, it seems that the astronomers conducting the so-called "Anglo-Australian Planet Search" were unable to observe one. It would be ideal to see one, though, because it would provide strong evidence something is actually there (they haven't actually seen anything besides the stars!), and tell the astronomers the inclination and radius (which would instantly give us mass and density of the planet to within experimental error).
  • Maybe you're just exaggerating, but:


    There is no water on Jupiter.
    Ummm, that's just plain wrong. Sure, our probe found less water than expected, but it dropped into a hot spot. Besides, do you think Shoemaker-Levy contained no water at all?


    If there is any oxygen at all there, it's in very trace amounts
    Well sure, everything that's not hydrogen or helium on Jupiter you might call "trace," since that's not really a quantitative term. Still, Jupiter is big enough that there is plenty of H2O and CO. I would advise against treating the Galileo probe's measurements as authoritative for Jupiter's entire atmosphere. There very well may be concetrations of oxygen in certain portions of that vast ocean of gas.


    There is no "solid" mass on Jupiter, unless you consider pressurized hydrogen a solid mass.
    Also incorrect. Jupiter is believed to have a rocky core. Do you really think that in the enitre history of Jupiter, nothing rocky ever hit it and sank through all that gas?

  • Proof and likelihood are two different animals. Evidence doesnt not always point to probability.
    And even if evidence did exist on earth, we may not even recognize it for what it is, or alternatively assume humans hands were those that created it.

    Alien life may choose not visit us apes, may decide the majority of us are far too superstious to accept an alien life form into our cultures. They may not even wish to colonize in the very human traits of greed, expansionism and imperialism, may not even need to due to their biology, society, or culture.

    Life is far too diverse to catagorize it so simply, and under our own definitions of what we "think" life may be, and in what forms it will take, how it will act, react, feel and think.

    Besides, and heres the good part, if this life does exist, and i most certainly believe it does, how do you know they believe in life outside their planet? They may think you a mythical being, they may think that I am a statistical anomoly because I should not exist. And even if they do know we are here, what makes us so important to visit. Frankly, id just drive on by.

    Historically, we are a dangerous race for first contact even in our own terrestrial matters.
  • Thanks for the link. Though I should point out that the authors note that tidal forces may sustain a smaller moon's geological activity for a sufficient period of time.

    Which makes me think. If there were a habitable moon due to some lucky combination of size, parent's orbit, magnetosphere, tides, etc. would its inhabitants sit around saying: it's so unlikely that these factors combined to make our world habitable, what are the chances that a planet in the habitable zone could support life? All the while not knowing that a *different* set of lucky circumstances had done so?

    My point being that even if it takes an intricate balance of physical factors to make life possible, the sheer number and variety of such combinations makes many such intricate balances possible. Just as there are many different intricate ecologies on Earth, and many of the creatures in any one habitat would go extinct from the slightest change, and yet all of these intricate ecologies support life in some form.
  • We're standing on a planet that's evolving and revolving, and going at 900 miles an hour...

    I think Monty Python refers to the speed of the Earth's surface at the Equator - but in knots (nautical miles an hour) not statute miles per hour. The Equator is roughly 22,400 nautical miles all around. Divide that by 24, and you get a speed of 933 knots at the equator. The earth's orbital speed would be:

    2 * 150,000,000 * pi = 942,477,810km

    942,477,810 / 8760 = 107,588 km/h

    In miles per hour this is:

    107,588 / 1.6 = 67,242 mph - just a touch faster than 900 mph!

    270,000 / 67,242 = a sedate 4 times faster than the Earth.

  • And you mean "tides" as opposed to "tidal wasves(sp?)", correct? Tidal forces on a moon of a gas giant would be very impressive, to say the least.

    That would depend on the orbit of the moon. A couple of Jupiter's and Saturn's moons are over 1 AU out from the planet, if I'm remembering the reference chart from "The Handbook of Chemistry and Physics" correctly. (Someone slap me if I'm remembering this wrong ;)

    The tidal force at such a distance would be less than what the sun does for Earth (varied also by the radius of the moon in question,) because the mass of the planet is likely to be a lot less than a star (or else it most likely would have collapsed into a star.)

    Still, if there were many moons around a planet this size, like Jupiter or Saturn, as well as the effects of the star in the system, this would all combine to create some interesting tidal charts.

    I'm not sure I'd like to sail a ship with a deep draft on a world like this.

    -Xiombarg

  • What the Hell is this "Zone"???? A region around 1 AU? NONSENSE! Earth is probably more an lucky aberration than a rule of the thumb. It is probable that it is extraordinary that Earth formed at such distance of the Sun with all the parameters to keep a large amount of liquid water on it. Look at the Moon for an example of what I'm saying... In fact the "habitable zone" should be generally be a bit more far away than Earth. I mean the highest probability zone. Because all this is a probability function based on the theories of planetary formation. It is considered that planets are formed from a planetary nebula. And that the "habitable zone" will be a region where water will have the chance to condensate AND later to keep its liquid form.

    In general, in the case of a sun-like star this would look like a probability function that starts at zero from the center of the system, keeps zero up to regions between Venus and Earth, sharply rises between Earth and the asteroid belt, and slowly lowers up to a region beyond Jupiter. We know that there were oceans in Mars. We know that the Moon shows Earth as being on the EDGE of this zone. We know that there is the high chances for Europe to have an inner ocean. And we have a hot Io showing that tidal phenomena may trick the whole game of temperature distributions. So if one searches for "habitable zones", then he should search for a region much larger then the Solar System and surely not at 1 AU. Mars lost its water for some damn cosmical impact that send into bubbling to Cosmos. And there are indications that, even now, water makes a good part of the landscape.

    Besides I don't see the good point to remark huge planets in highly elliptic orbits. Because they are inside the 1 AU? And what about the escape velocities produced by these orbits? We surely will not find Extra-Jupitereans. We can only rely on the possible sattelites around these planets. And these planets will have very thiny chances of possessing big sattelites with enough conditions for life. Because they need to be big and fat. Or else they will be cooked like the Moon.

    Besides what about the chance of Jupiters at Jupiter's distance but with Mars-sized satellited. It is quite possible. And we know that the tidal game may trick the production of enough heat to give habitable conditions to these planets. While these would be exceptions, they are not far from the conditions we even see on Jupiter. At least everyone says there is a good chance to find Life in Europe. There is no arguments to dismiss this fact, on the contrary. And sincerly Life doesn't exactly need the surface of a planet to live and survive. So "underground" habitable zones may extend even further...
  • Here here, I couldn't agree more sir
    I think most humans tend to catagorize life quickly and easily as "something like us" or "something chemically/geneticall/biologically" like us" in terms of needs/structure.

    Extraterrestrial life may well defy definition for a long time, simply because either we havent experienced it yet, or we have and didnt recognize it for what it is.

    To truely quantify something like life in such broad terms, and compare it to a universe, is as hard a task as has ever been set, because the only baseline we have of life, that we can compare to what we may find, is what we already have on this small rock. Compared to a galaxy, we have a rather small control group.
  • I can see it now.... It's the 23rd century and all the surfers have left earth to ride the waves on the fifth moon of HD179949. ;-)


  • The article states that we are able to detect these planets only because they are so large and close to their stars, that their gravity causes the stars to appear to "wobble".

    It will probably be quite some time until we can determine things such as rotation, revolution, presense of moons, virtual communities, etc...

  • Dearest Flower,

    You are absolutely correct. Although there is water on the moon, it is innaccesable. It would be much easier to get it from Jupiter, obviously. 120 million miles of space is a much smaller barrier than 1 mile of rock. I don't want there to be the same barrier between us though, so please reply and tell me what you think of this.

    Forever Yours,

    KTB

    KTB:Lover, Poet, Artiste, Aesthete, Programmer.

  • The article fails to mention that the quoted masses are just lower limits, because the inclination of the planet orbits to our line of sight is unknown. One would need to divide by the sine of the inclination to obtain the true mass of the planet (as the inclination can range between 0 and 90 deg, its sine is between 0 and 1).

    While very large masses can be excluded by other arguments (the planet would be more luminous than the parent star), there is still a fairly large range for the planet mass.

  • Has any one read a meeting with Medussa? or it is kind of mentioned in adoyysey II by Arthur C. Clarke.
    Basically he makes many references to these giant animals (or plants) in jupiters atmosphere, and gives the facts to why they could actually be there. They are extremly light because they are made of giant bubbles or something.
    There is a whole system going on with Grazers and herders and Carnivores.
    Very interesting, anyone who has read the book lately care to enlighten?
  • One problem I have yet to see a satisfactory explanation for is this; since most of the stars in our galaxy are older than our own by millions of years, if there were any other intelligent races with anything in common with our mindset at least some would have evolved long long before us.

    Even with todays technology, and completely disregarding the possibility of FTL travel, the capability of building generation ships travelling at a fraction of the speed of light would be within grasp of a civilization similar to our own. If a species evolved even some hundred million years ago they would have managed to populate most of the galaxy within a short period of time (on the astronomical scale of time). This should lead to at least some sign of intelligence, but why isnt some found?
  • > that there should be millions (billions?) of intelligent races, or just one, us.

    Just us? You're kidding, right? :)

  • grumble.. I should remember that the circumference of a circle is not pi*r^2, but 2*pi*r. duh. I was only off a factor 12 billion.. *sigh*

    //rdj
  • If I remember correctly, Jupiter-size gas giants usually don't have a solid surface, because they mostly consist of light gases like hydrogen and helium - those are the most abundant elements ind the universe. Earth and the other small planets in the solarsystem have lost most of these light elements, because their gravity is not high enough to prevent them escaping into space. Only the hydrogen that is chemically bonded to heavier elements, like in water, has not been lost. Life forms in those gas giants - if they exist - would probably be very different from terran life. A gas giant has at most a very small solid core, where the pressure is so high that even hydrogen would be solid. I don't think anything could survive there. Possibly something could live in the upper atmosphere where the pressure is not so high that it crushes everything. I don't know if such life forms could ever develop any technology. If they ever attempted space travel, their problems would be daunting - not only escaping the gravity of their planet, but even constructing a ship that can contain their high-pressure atmosphere in a vacuum. But gas giants in the solar system have a lot of moons, some bigger than Earth's moon. If those extrasolar planets have moons too - we don't have the technology to find them yet - they would probably be able to support life under Earth-like conditions. Stefan
  • I totally agree. I notice scientists are always looking for planets with evidence of water on them. Well, yes, as far as we know, things need water to live. But who is to say that there isn't a planet out there with some other form of life that doesn't need water to survive. Just because today's science says that organic matter needs water to live, doesn't exclude the possibility that there might be life out there that doesn't need water to survive. Considering the size of the universe, how could scientists possibly rule this out?
  • This hypothetical civilization colonizes the galaxy in a few million years?

    And in all that time, this race has no wars, no economic hard times, no diseases? That could slow them down. It could be that it is culturally a very difficult thing to do, to colonize other planets, light-years away. Given the cultural drift that can occur in two societies that are isolated and unable to communicate, the likelyhood that wars would erupt seems almost a guarantee.

    And, even if it IS NOT possible to travel faster than the speed of light, what if it is not technically feasible to colonize another world at all? I mean, we like to draw parallels with sailing the Santa Maria across the Pacific, but it's not quite that simple. It takes a huge amount of resources just to get a paperweight into orbit. Now, how about putting a ship large enough to be home to 1000 or more people for generations, into space, and across the gulf of light years - barring again, disease, cultural instabilities, technical difficulties, etc. Yes, we all want to believe that these problems can be surmounted by a sufficiently advanced civilization - and I'm not saying that they can't. We don't know that. But what if, just what if, that IS the case, that as far as technology goes, we've gone just about as far as we can? What if fusion power is not feasible? What if 1000 people on a generation ship kill eachother? What if life on a generation ship is not sustainable, or requires a much larger biosphere than can be constructed without threatening the economy of the civilization that is building it? What if, 50 years into the journey, an airlock seal blows because a greedy contractor cut corners? There are a lot more reasons why this wont work than simply a civilization blows itself up with atom bombs. And even if it can be made to work, what if it's just a lot harder than we think it is. In that case, the rate of colonization may be much, much, slower than this theory states.

    These estimates, that the whole galaxy ought to be colonized by now, in my opinion, are far too optimistic. It has been theorized, how it could be done, but was the full economic impact on the civilization measured? Were ships designed beyond the basic features and principals? This ought to be done with current human technology, to see if it can be done at all. We're not even sure if we can technically put a human on Mars and bring them back - there are many unanswered questions, such as, radiation, human endurance, margin for error, the martian environment (dust, it seems, will be a very seriously major problem, as yet, unaddressed).
  • > Well Earth managed to keep life "alive" because it already had lots of water back then.

    Yeah, nobody's asked about something that's pretty unique to Earth, namely: "has to get whacked by a Mars-sized impactor real early in its development".

    Any ideas if that impactor was ice-rich and if any water vapor from impact could have hung around as the resulting mess cooled (and produced the Moon)?

    Seems to me the "big whack" comes in handy for:

    The moon - nice tidal energy pumps to stir the oceans

    The water (maybe, as I'm wild-assed-guessing in my first paragraph)

    The seasons - the 23-degree axial tilt that lets the sun drive energy back and forth across the surface of the planet I'll accept that big whacks are pretty common (Uranus' axial tilt, etc.)

    This doesn't cut down on the number of habitable planets from the point of view of a colonist from a technologically-advanced civilization.

    But if it's a major factor (or an essential), it may cut down significantly (like, say, eliminate 2/3 of the planets - asusming Earth, Whatever-Got-Mushed-And-Made-The-Asteroids, and Uranus - 3 of 9 whacked planets) on the number of habitable worlds on which life actually evolves.

    (Yeah, the only way to find out is to do lots more planet-hunting, huge-ass interferometry, attempt to get spectra and what-not... the nice thing is that younger /. readers may actually see the results of the research in their lifetimes...)

  • This should lead to at least some sign of intelligence, but why isnt some found?

    I think you've hit the nail, this is the real question of life the universe and everything. I find the application of Occam's Razor to this subject is essential and produces some interest possibilities.

    My personal guess, is that the universe is a much more dangerous place than we currently believe, and that consequently minimal sentinels survive to leave an impact. The universe should be teaming with life, but observational evidence suggests it's rare or unique. It seems to me that many scientists shy away from the uniqueness conclusion, because of the obvious religious connotations. However, much [all?] of the evidence suggests we are [or nearly] unique, at this time.

    Also we seem to believe we are safe from extinction, but are we ? To me it seem we are constantly perilously close to doing the job of self annihilation, this also presents and an interesting angle on biological survival strategy, the R-K curve.

  • I remember seeing an interview with some members of a panel that was looking into likely forms of extraterrestrial life. They basically concluded that any life form not evolving with a similar composition and under similar circumstances to our own would be sufficiently different from us that we would have a difficult time even distinguishing it AS life. If you don't know what to look for, you'll have a terribly difficult time finding it. First looking for conditions and life similar to our own seems entirely logical. Remember, sci-fi is just that - fiction. LEXX PS - I know, I know, some reality has come of our fictions, but we have no warp drives, replicators or transporter beams, and likely won't for quite some time, if ever.
  • not only is tidal locking a serious problem, but as others pointed out, variations in temperature due to varying distance to the sun, or shading by the main planet would also have some harsh effects.

    Also, IIRC, Jupiter has some pretty intense radiation belts. Intense enough, that they pose a challenge to probes navigating the moons. IIRC, Gallileo had some hard resets when it passed through them. Now that doesn't mean that life cant exist, but all of these factors together make it unlikely to be stable - in other words, able to undergo speciation, let alone, develop into something that can post on slashdot.


  • And it probably came from the little green men peeing in their corner of the universe.


  • This [slashdot.org] = this [slashdot.org].
    Martin Spamer, no kidding.

  • the laws of probability say there SHOULD be other forms of self-replicating material (aka simple life) out there. have we heard anything to suggest there isn't or can't?
  • These jovian type planets in the habitable zone of their stars may have tidally-locked moons that are dense enough to harbour life. In our own solar-system, Jupiter's moon Europa is suspected of having a liquid water layer under an ice crust, maintained in that state by a constantly deforming rocky core.

    Larger mars-size satelites (or even larger earth- or venus-sized ones) could be orbiting these planets at distances that lock them tidally, or further out, giving them an even more tectonically active crust than we have as a result of our moon.

    In any case, such a world (they wouldn't technically be planets) would have all the same ingredients for life that we do, just in varying proportions, possibly leading to life, not as we know it, but at least recognizable as such by us.

    --
  • The seasons - the 23-degree axial tilt that lets the sun drive energy back and forth across the surface of the planet I'll accept that big whacks are pretty common (Uranus' axial tilt, etc.)

    The seasons don't do anything to promote life. By far the greatest concentrations of life in the tropics; both on land and in the sea, and they don't have discernable seasons. In fact, seasons are a hurdle to life: places with the largest seasonal differences (like the arctic) have the least biodiversity.

  • Here here, I couldn't agree more sir I think most humans tend to catagorize life quickly and easily as "something like us" or "something chemically/geneticall/biologically" like us" in terms of needs/structure. Extraterrestrial life may well defy definition for a long time, simply because either we havent experienced it yet, or we have and didnt recognize it for what it is.

    Agreed. And it's possible that some other forms of life could be so unlike us that we wouldn't even recognize them as life. And the same with them for us. It might even be impossible for us to even see each other.

  • The Drake Equation was developed by Frank Drake in 1961 as a way to focus on the factors which determine how many intelligent, communicating civilizations there are in our galaxy.

    Exactly. Drake had no illusions that the equation could answer the question. It was just meant to clarify the question, which it does quite well.

    Any "solutions" I've seen of the equation were plainly tentative -- "If I'm right about these values, then this is the result." Sloppy thinkers/writers might not be clear about that, and -- at least as likely -- sloppy readers might miss the qualifiers. But that's not a problem with the equation itself.

  • Well taking a good look at some of these orbits I would doubt we could find such repositories. zi mean the high elliptical ones. First we know that at 1 AU and less, Moon-sized moons would be virtually cooked by the star. And every planet with a wrong wobble would get into the same fate... Then we should take into account the huge tidal forces produced by these orbits. So probably most moons would look more as hot melted cheese. And then we should think if there are such moons at all, as the escape velocities would be tremendously high for large moons.

    Considering the number of such elliptical planets, chances are much lower than one should expect...
  • If the planets are as big as Jupiter.. Then the creatures would be pretty small. Or very muscular, with all that gravity. Wouldnt that be great, a race of super strong aliens, lets not piss them off ;). Or maybe we just have some fungus..

    Ennui [ennuiweb.com]

  • Even though there may be planets around other stars with the potential to develop life or even simple forms or life, it does not naturally follow that there will be intelligent life on other planets anywhere near us.

    For most of earth's history, life was in the form of single-celled organisms. It wasn't until recently (in geological time) that multi-celled life came into existence. Further, humans only developed after a comet slammed into the earth and wiped out the dinosaurs. Technology is another element that must also be developed in order to communicate beyond one's planet of origin. The probability of all these developments occuring with significant frequency is low. Therefore, the likelihood of finding intelligent life on other planets is very low.

    Is there intelligent life somewhere in the Universe? Most likely given the estimated size of the Universe of 100 billion galaxies with 100 billion stars each (10^22 stars).

    Is there intelligent life somewhere in the Galaxy? That's a tough one. It is possible but it is not probable that we will find it. Even if intelligent life developed somewhere else in the galaxy, it may not have developed at the same time we did. We've only had the technology to communicate to other planets for 50 years. Further, there is also the issue of huge power requirements to communicate across long distances in space which is yet another obstacle to finding intelligent life.

  • I'm not sure if this was a troll or not, but I'll feed the little blighter anyway...

    >I mean, when the model considers a star to be made from hydrogen, helium and "other stuff" how can you take it seriously?

    You can take it extremely seriously. Stellar modelling codes do just fine for many types of stars by representing their constituents as hydrogen, helium, and 'all the other stuff', misnomered as 'metals'. An astronomer's Periodic Table looks very simple - H, He and Z, where Z represents all the heavier elements lumped together. Since most stars are virtually all H and He, the models do spit out good comparable stellar models.

    >Whilst these discoveries are great for further illuminating what's out there, they yet again cast doubt on much of astrophysical "theories".

    No, they don't. Before, planet forming theory was difficult because the ONLY data points were from the Solar System. Now we have more data, its back to the computers and models they go. An ounce of observation beats a ton of theory, but then isn't that the case for all science?

    > We need to remember that as a subject, it's one of the shakiest scientific disciplines around.

    Not unless you count biology, but then is that a science? *grin* Anyway, the practical classes in astronomy are absolute bastards to do... "Take 10^30 kg of Hygrogen, and allow to settle for 10^10 years. Write down your observations."

    Matt (about to get lynched by a horde of angry biologists).
  • very muscular, with all that gravity. Wouldnt that be great, a race of super strong aliens, lets not piss them off

    Piss them off all you want, if they ever came to earth they'd be very uncoordinated in a low gravity environment. They might be super strong, but they'd be way too awkward in our gravity to put up a good fight.
  • Gravity scales lineary to the ratio between different radiuses for planets with the same density, so even if they have like, 3, 4, or 5 g-force, life can be developed on them if the right materials are combined in the right temperatures.
  • I love it when the Drake equation is invoked as a way to calculate a meaningful result with some relavance to human or alien civilization.

    The Drake equation is calcualted by multiplying seven terms together. 3 of those may be obtained from reasonable sources in astrophysics and planetary formation research (albeit they are continually changing as we learn more!). The other 5 terms are picked essentially at random, and therefore have no meaningful value.

    The only thing the Drake equation is good for is exploring the relative impact that manipulating various terms may have on hypothetical contact. Due to 5/7 of the numbers being completely arbitrary, it has no value beyond that limited application.

    Use of the Drake equation is a great example of "subjective" science. Adding an additional term defining the probabability of the society creating Twinkie's and eating themselves to death in a cream filled orgy before transmitting would have no detrimental impact on the reliability of the answer.
  • Yes, for if we find such a place, with water, air, light, and plants... but, with major earthquakes... we'll never find life there. Except for the plants... or did you mean silk plants?

    He obviously meant power plants, who in their right mind would live in some place without electricity?
  • You are absolutely correct. Although there is water on the moon, it is innaccesable. It would be much easier to get it from Jupiter, obviously. 120 million miles of space is a much smaller barrier than 1 mile of rock. I don't want there to be the same barrier between us though, so please reply and tell me what you think of this.

    There could be easily accessible water on the moon, ice from comet impacts at the bottom of craters that are never exposed to sunlight. But this isn't proven yet and it would not be much in any case. If I remember correctly, the Saturn rings are mostly ice - that would be the easiest way to get lots of water, if there are big, soldid chunks of it. You could fix a large, nuclear-powered drive to it - that could use part of the ice chunk as reaction mass to move it to any place in the solar system you like.

    Stefan

  • If they are as big as Jupiter it's gonna be difficult to support life (like we know it).

    First of all: Planets of these sizes are mostlikely to be gas-giants. And it's damn difficult to built houses on gas-giants. But if it is a solid planet grafity is gonna be to strong for normal lifeforms to walk around.

  • According to the US Space Act (1958), space photos suggesting the existance of extra-terrasials are not for the eyes of the public.

    Lack of signs? I wouldn't call a 20km-long object showing on a european air controler's radar, a lack of signs...

    About what about strange lights and hugh cylinders orbiting Saturn [simplenet.com]

    ? Maybe you mean, lack of contact.

  • I think we should all keep in mind that if there are any other life forms out there, they don't necessarily have the same needs for survival as we do. So far in our research of the universe, we havn't came across any other planet that is exactly like Earth yet. Not saying there isn't any out there, but I think we should be more open to the other needs that may exists out there, that perhaps don't need water. Our sciences are based on our small spec of paint, on the canvas of the world, and is very limited.

  • moons (Score:3)

    by robwicks ( 18453 ) on Tuesday December 12, 2000 @02:26AM (#565619) Homepage
    I've heard that the moons of such planets are the more likely repositories of life. The moons would have liquid water, and a gas giant might be a source of additional heat if they emit more heat than they take in like Jupiter does in this solar system. I do wonder about sunlight, though, with a gas giant providing eclipses.
  • Don't forget the moons.
    Most of people there are claiming that
    jupiter-sized planets are too different to either have any life in it or then it will be so very different there is no way for us to understand those beings, and they are probably right but almost all seem to forget the moons.
    Jupiter sized planets can have several Earth sized satellites. Think about Europa, or Titan, even those are speculated to maybe host life, yet they are very cold and very far away from then sun. What if Jupiter-sized planet would be at Earth distance from its star and have Europa-like moon?
  • Hah! Got me there. That's what I get for posting after 4 hours sleep. Hit submit instead of preview, too. :)
  • Yeah, we know everything about big objects like, black holes, galaxies, and the Universe itself . . .
  • Wow. Amazing. Well, since you took the time to be sarcastic, snide, and insulting, why don't I return the favor?


    Whether or not Jupiter has a solid core is still being debated. Most notable astrophysicists agree that there is no way of knowing if Jupiter has a core mass or not. The last time I heard anyone argue FOR the solid core was 1989.
    Of course it's impossible to know for certain if Jupiter has a rocky core without direct measurement, and some people may not believe until they reach out and touch it with their hands, but that's not happening anytime soon, and is irrelevant. As for the '1989' date, you seem to be implying that no one believes in the rocky core anymore. Perhaps, then, you should try the following experiment. Go to Google. Enter "jupiter rocky core". Press "I'm feeling lucky." See JPL mention rocky core. Or, just press "Google Search" and read links that deal with the concept more directly. This, of course, does not prove that the core exists, but rather goes to refute the idea that you present above, which is that scientists no longer believe that it exists.


    Maybe that's just me. You're right, though, it is believed to have a rocky core. But it is also believed to not have one. You tell me to disregard Galileo's data but you don't have a problem quoting implied data from Pioneer 10 and 11. If you meant that YOU believe it has a rocky core, I would like some more justification.
    You're right. While you (I assume you wrote the post to which I replied, AC) can come out and state that 'there is no "solid" mass on Jupiter' and give no justification whatsoever, mere mortals such as I must give it. And I didn't say that one should disregard Galileo's data, merely that not finding the expected abundance of water along the probe's entry path (which infrared images revealed to be a relatively unclouded area) does not imply a total absence of water on Jupiter. I never argued that there was as much water as we originally thought, merely that there is some water.


    What "rocky core" do you propose can sustain it's solid phase at the awesome pressure and temperature at the core of Jupiter, after being immersed in liquid metallic hydrogen?
    Sure, the temperature is an issue, but the "awesome pressure" would encourage most materials to go into solid phase (except for weird ones like water, of course). And what the heck does the liquid metallic hydrogen sitting above it have to do with anything? Are you proposing that it would dissolve the core or do you just think the words "liquid metallic hydrogen" are going to convince me that you know what you're talking about?


    Impact events would make no difference one way or another, unless you are implying that Jupiter collided with another planet. That could give it a core mass.
    Oh, sure, that's scientific. So, an asteroid couldn't do it, but a planet could? What about a really big asteroid, or a really small planet? My point is: what magic line determines that a body is big enough for you to dub it a "planet" and simltaneously allow your imagination to grant it the power to give Jupiter a rocky core, where all other impacts "would make no difference"? Give me a break.


    Where did this theoretical planet come from? Extrasolar?
    Oh, sure... the only bodies around while the solar system was forming are the ones we see today, is that what you are saying? Your argument keeps getting better and better.


    Most of the extrasolar planets we have ever discovered are gas giants themselves, and larger than Jupiter to boot.
    Right, this is irrelevant, but I suppose you believe that those numbers are in no way skewed by the detection methods currently in use? Obviously if we look for planets by looking at the gravitational wobble of stars, we're going to detect massive ones that orbit close to their stars. Heck, that much is even in the article to which this story referred, if you were unable to figure it out for yourself using basic physics. If there were any previous indication that you were scientifically qualified, this last paragraph is squashing that.


    Which would mean Jupiter used to BE an extrasolar planet, and collided with a smaller planet with the orbit Jupiter now holds. If that is your theory, I advise you to examine the feasibility of it.
    Wow. Where are you getting these ideas and whatever it is that you are smoking? That's quite a ridiculous theory that you put in my mouth, and I will shortly spit it back at you.


    Well that was fun. Let me take some time out at the end here, leaving all the problems with what you just said behind, to explain the problems with your initial argument. The bottom line is that you have made statements that cannot be reasonably defended.

    You say that "there is no water on Jupiter" [emphasis mine]. Now, I could talk about solar oxygen levels and the presumed abundance of oxygen in the early solar system and so on, but I don't have to. I'm even willing to believe that Jupiter has a relatively low oxygen abundance in its atmosphere. Nevertheless, we all saw a bunch of chunks of frozen water slam into Jupiter a few years back. Discarding for the sake of argument the idea that there was any water present on Jupiter before the impacts, if one single molecule of water from the impacts survived, then there is water and it's on Jupiter, so you lose; end of argument.

    Similarly, you say "there is no 'solid' mass on Jupiter". Again, if there is a single speck of dust on Jupiter, you lose; end of argument.

    The smart thing to do would have been to admit that you were exaggerating (that's why I gave you that "out" at the top of my post), and then we could have settled into a more reasonable discussion of planetary formation and elemental abundances. Instead you went off on these weird tangents, became insulting, and capped it off with ridiculous statements like the one about extrasolar planets mostly being giants, which thoroughly discredits you, made it a joy to write this reply, and makes it certain that neither I nor anyone else will pay any mind to anything more you have to say.

  • I don't know if I'm feeding the troll, or what, but hold on just a second. You state nothing but generalization, ie, "People forget that..." or "Both branches religiously attempt to..." in a manner which is, IMHO, patently absurd. Disagree with specific theories --fine, challenge their assertions --fine; make blanket statements about the motivations and methodologies of the practioners -- bullshit. Astrophysics is nothing more or less than the application of ordinary everyday physics to astronomical phenomena; casting aside for the moment certain special cases, you can't argue one is flawed without casting aside the other as well. It may surprise you to note (maybe not, I dunno) that the vast majority of astronomers are not cosmologists; that most study the births and deaths of stars or the generation of magnetic fields or the composition of the interstellar medium or some such other random topic -- the point is that in very few cases does astrophysics involve fundamentally new physics, and when it does, there are usually many people outside the astrophysics community engaged in an attempt to understand such physics.

    Even the "example" you quote, that of "how the Universe came into existence," about which you say, "the fact of the matter is that we know nothing..." is a poor one. Like all scientists, astrophysicists have formulated a theory (namely, inflationary Big Bang) which explains certain observational facts, makes certain predictions, etc.; furthermore (and quite significantly), it is generic in the sense that the results it predicts are not sensitive to a large number of parameters. I could yak on about this ad nauseum, but briefly, observational corroboration includes the existence of a Hubble flow (velocity is proportional to distance), the existence AND detailed properties of the cosmic microwave background (to wit, its isotropy to one part in 10 ^ 5 or so, the fact that it has the spectrum of a perfect 2.7 K blackbody, and the manner of the very small-scale anisotropies), and the ratio of light element abundances. Show me another theory that predicts all these things, in a natural way (ie, without invoking 27 free parameters to tune as you wish), and I'll listen to you; but hell, do that and you've probably won a Nobel anyway, so why bother with me? Furthermore, the physics of the Universe before nonlinearity should actually be very well described by "normal" physics -- and if it's not, that's a fundamental problem, independent of the application; the kicker, though, is that we have no solid evidence that the physics here doesn't work.

    To sum up, my NSHO is that you are a) unclear about what exactly astrophysics entails, is, and relates to, and b) are unable to back up your broad claims of illegitimacy with fact. Your one anecdotal evidence of the evils of astrophysics, regarding the greenhouse effect on Venus, is so incidental as to be laughable: I know jack about the atmosphere of Venus, or about greenhouse gases in general, or really about planetary science in general, but then again I don't really have to; the vast majority of topics in astrophysics have absolutely zero to do with it. My totally biased opinion is that Carl Sagan probably has given more thought to this than I have, or than you have, or even (perish the thought) than Gunnar Heinsohn, whoever the hell he is. Your argument is like suggesting that if a chemist can't predict the bonding properties of C60, all of chemistry is flawed.

    Have a nice day. :-)

  • Like it said in the article, Earth-type conditions are more likely to exist on sattelites of the gas giants. Given that both Saturn an Jupiter have moons of roughly earth size, I think it's probably a good bet that these exoplanets may, as well. As I remember it, tides are considered useful in the life-generation process, so being the moon of a large planet would make life even more likely.

    The other question that comes up for me is: Did earth start as a gas giant? I'm thinking that what we're living on could easily be the evaporation residue of something the size and composition of Jupiter. If so, then what we're seeing could well orbiting those suns could well be a precursor to an earth-type planet.
    `ø,,ø`ø,,ø!

  • Density does effect gravity. This is because gravity is inversly proportional to the square of the distance between the two masses. While this relationship is difficult to model for a vastly large body, like th Earth, you can simplify it by thinking of the distance being to the center of the Earth. Mass closer will exhert more gravity, mass farth will exhert less, but it mostly works out. If you strech the mass of the Earth over 10000 times the volume (no where near the size of a nebula, BTW), you would get 1/(10000)^2/3 ~= 1/464 times the gravity (the cube root is because it is square to the distance, which is found by the cube root of the volume).

    Of course, this isn't to say that density is the actual important factor. It is of course, Gravity. A 10000 times larger body with 464 times more mass would have the same gravity and could sustain an atmosphere like earths.

  • If it shows up on radar, then this is obviously conclusive proof of its existence. On the other hand, other sightings have not been confirmed by radar, because of the unknown creatures' vastly superior technology, which the U.S. government obviously derived stealth technology from.

    The civilization of these beings has existed for far longer than any human civilization, for so long that they have managed to create technologies enabling faster-than-light travel, incredibly resilient materials, and apparent contradictions of the laws of conservation we know of, and they choose to use it to hide from us constantly and pick up Billy Bob Hick from Buttfuck, Tennessee every couple months to take him for a ride and poke at his innards a bit.

    Most of us humans are obviously too unevolved to understand their motivations. Only those few who are willing to believe, have the capacity to understand, and are wily enough to avoid being killed off by the U.S. government can possibly tell the truth. Amazingly, most of these persons have little beyond a high school education, live in trailer parks in Middle America, and have never seen much outside the city limits where they were born. It is probably only due to this isolation that they are able to avoid the tainting influence of the doubting Thomases and the talking heads of the military-industrial complex in the scientific community. That and their tin-foil hats.

    If you can explain away a sighting, can you explain the face on Mars? If you can explain the face on Mars, can you explain crop circles? If you can explain crop circles, can you explain these marks on my lawn? The bump on my head? The mark on my stomach?

    All evidence works in favour of the hypothesis, and any lack of evidence can be explained by conspiracy theory. There is no contradiction.

    Thank you for your time, cunt.

    Love,
    Slashfucker

  • Perhaps you've seen videotapes of Dr. Julius Sumner Miller... the rather animated British professor who would teach lessons of physics a few decades ago. He used the phrase in his video series once.

    It's an antiquated expression, whereas 'sublimes' is more accurate and more acceptable in modern circles. 'Camphoring' is more likely from Middle English than technical. It uses a substance to describe a process, similar to the way 'ice' implies the substance 'water,' but could describe other substances solidifying.

    The important thing is that a planet must have a good degree of pressure. On tall mountains, you can boil water away in a paper cup, but on a depressurized surface like Mars, you couldn't get water into liquid form to begin with, unless it is pressurized. On the moon, they're not about to look for liquid water, but it is believed that it can exist in solid form (ice) located in shadowed wells.

  • We're here !!!!! Seriously though, given the fact that modern man appeared suddenly all over this planet 60K or so years ago, with language, pottery, alphabet etc indicates a possibility that we just might have colonised this planet. Some Polynesian tribes (isolated from Inquisitors) believe that we all lived in an egg and hatched to colonise the world.

    I'm not a archelogist, but apparently there are almost no remains of human residence from a period of -60K to -800K (then you have remains of various Neanthertals). 60K years ago mankind appears all over the world, with formed culture, pottery, basic woodworking skills etc etc.

    Food for though.
  • 10,000 times the volume of Earth is a bit extreme... Saturn is just one order of magnitude less dense than Earth. If Earth's mass were distributed to even 100 times the volume, the problem becomes one primarily of pressure. Liquid water must exist at a pressure above the triple-point.

    Sure, we can discern some of the many differences between atmospheric density (pressure) and mean density of a planet's various layers... There can be/is great variety in each planet's frame. If you vaporize the metalic core, or even substitute it with an equivalent mass of atmospheric gases, what have you got? You'd have less than 1G coming from the earth-equivalent mass (Newton's Law of Gravity says the increased distance, *squared*, would proportionally reduce the gravitational force.)

    Heating and cooling poses interesting questions... A solid mass stabilizes a lot of the mean temperature. Would the gases quickly take off, cooling the nebula in disappation? Would they heat like a greenhouse, and begin radiating like a gas-giant? Probably both, but in what portions? Actually, a scientist friend of mine points out that space's so-called vacuum is actually rather hot to the gases travelling through it... the free-flying particles have neither the shade nor the dense gravity to slow their velocity. Of course, a solid mass in shade might not notice, unless it were small enough for the exchange with light gas to transfer comparable tempurature/mass.

    It takes a lot of gravity to make a gas giant. If you could stand on the surface of the Sun and sense the pull of distant planets, Jupiter has more than 11 times the pull of Earth, despite having four times its distance.

  • 1. Starting an uncontrolled nuclear chain reaction requires lower tolerances than controlling a chain reaction that is just subcritical. This means that fusion bombs are technologically simpler than nuclear rockets or fusion power plants.

    2. Elliptical orbits with periapsis belows a planet's surface are lower energy than circular orbits at the ellipse apogee. This means that ICBMs are technologically simpler than orbital rockets.

  • Science fantasy authors love to write stories about "silicon-based life", but anyone with sufficient training in biochemistry can tell you silicon won't work as a basis for organic life [scientificamerican.com].

    And if you're going to consider even more exotic ideas ("photonic life" a la Star Trek, or neutronium life), you might as well be discussing ghosts and gremlins. They're just as plausible.

    The main candidates out there are carbon/water life vaguely similar to stuff on Earth, and possibly machine intelligence (previously built by carbon/water life).

  • >The planet, which has a mass that is 84% of our Jupiter, orbits the star in only three days. hmm.. a 72 hour year??

    The inhabitants would have significant advantages in the world of e-commerce. They are already running on "internet time".

  • This doesnt spell out very fun for us... if it turns out the traits that create civilizations of our type lead to pretty much assured self-annhilation.

    I suppose here is as good a place as any to wrte this. I have become quite fed-up with this notion that war will somehow lead to the end of our species. Really, I find it quite ridiculous.

    War is a rotten thing with a lot of bad effects--it's very rarely worth the expense. But there's always at least one winner left at the end. What about nuclear war, in which two sides could conceivably destroy each other utterly? It won't happen. Nuclear weapons will not be used on a large-scale basis until mankind is spread across several planets. And when that happens nuking one planet will do nothing at all to that other planet.

    Nukes may be used on a small scale here, but I doubt it. Too much stigma in every nation. Pity, too--some of the clean weapons are, quite frankly, amazing. FAEs are still cheaper, though--and they don't give the nuts as much of a scare.

  • How can one "turn" a sterile ball of rock into a sterile ball of rock? And who cares if we do?

    Don't just absorb the environmentalist line, think about it. They're only about half right.

  • Mare Infinitus. Endymion, damnit.

    Wait, that's four. Damnit, now it's eleven.

    --
  • The Pressure-cooked comment doesn't draw these "completely unrelated" factors as the only variables... but rather as the major variables working in Earth's favor...

    If density were indeed unrelated to atmospheric pressure, why doesn't Ceres have an atmosphere? Density, mass, and temperature are three, and not the only three, variables that influence such a thing. (A superdense asteroid the size of Ceres could hold a dense but shallow atmosphere.) Wouldn't Venus' atmosphere solidify at an increased distance? Would Titan's boil away if too close?

    If Earth had its present density, but size were increased to that of Jupiter, it would lose the low gravitational mass I speak of.

    Picked apart like hair-splitting equations, these relationships are indeed incomplete. But taken together, like the balance of relationships as which they were presented, they illustrate a useful component of the facts we'd need to address in colonizing other worlds.

    And 'chaos' is not from a cult or religion, but from ancient greece, the birthplace of western civilization. Granted, many of those guys believed that life came from the chaos of fire, and to fire it would return. But if relating the word chaos to fractals or dynamic energy wigs you out, then you may find difficulty with certain fields of modern mathematics. (I'd also suggest avoiding 'Jurassic Park.') ;-)

  • grumble.. I should remember that the circumference of a circle is not pi*r^2, but 2*pi*r. duh. I was only off a factor 12 billion.. *sigh*
    Well... that's close enough for NASA.

  • Hmm.... so the maximum distance that a planet could orbit our Sun and be spontaneously habitable (i.e. without terraforming) is about
    1.25 AU.

    At this distance a Terrestrial planet with the standard inventory of CO2 and H2O would have started off some 4.5 billion years ago with
    a surface temperature and pressure very similar to modern Mars. As the sun warmed, the planet would slowly warm too. After about 1.5 billion
    years, the planet would thaw enough for liquid water to be stable at the equator, and the process of conversion of CO2 to carbonate rock would
    begin and the extensive CO2 pole caps would begin to disappear. Once consumed, their depressing effect on temperature (caused by the
    reflection of sunlight back into space) would be removed and the planet could warm up appreciably. At the present day, such a planet would have
    Earth-like temperatures but would need a large proportion (15%) of CO2 in the atmosphere to acheive this. 15% CO2 is poisonous to higher life
    forms, but extremophiles can survive and if this was the planet's atmosphere, then life could well evoilve to tolerate it.

    There's no reason why life couldn't evolve on a colder planet, further from the Sun. But it would be forever restricted to underground habitats
    where volcanic activity warmed the ground. In nature, this life would resemble extremophile bacteria and algae on Earth, which appears to have
    been the first form of Terrestrial life from which everything else evolved.
  • We're standing on a planet that's evolving and revolving, and going at 900 miles an hour...

    My (very approximate) calculations show that the planet's travelling at about 270,000 miles per hour, 300 times faster than the earth, if my Monty Python is correct.

    MY calculations are:

    2*6,000,000*PI = 38,000,000 kilometers
    38,000,000/72 = 530,000 kph
    530,000/2 = 270,000 mph
    270,000/900 = 300 times faster than Earth

  • You're thinking of Hal Clement's Mission of Gravity, but you seem to have gotten a few details mixed up with Robert L. Forward's Dragon's Egg (Mesklin in Mission of Gravity was a super-Jovian planet which rotated so fast that it was extremely flattened at the poles; the setting of Dragon's Egg was a neutron star).
    /.

  • Overclocing a planet (Score:3)

    by Spoing ( 152917 ) on Tuesday December 12, 2000 @05:05AM (#565676) Homepage
    270,000/900 = 300 times faster than Earth

    ObHakorz comment:

    1. 'D000d! I'd like to see the heatsink on that bad boy...puts my Athlon to shame.'
  • Considering the number of such elliptical planets, chances are much lower than one should expect...

    As your looking at nature of the planets being discovered, you need to consider the methods used to discover them. From previous stories, I believe the most popular technique is to analyze the 'wobble' that the planet's orbit creates in the host star. Would circular orbits create as much of a wobble as a highly elliptical one? If there is a difference, then a skew result in findings is to be expected.

  • The great way to eliminate over-consumption is to get rid of subsidies. In a healthy market over-consumption leads to increased prices leads to decreased consumption. those societies which were destroyed by over-consumption generally had no check on the actions of their members, like money, or had an artificially-supported market somewhere. Bad bad bad...
  • >Earth is the most dense planet of our system.

    This is not correct. Mercury is the most dense planet in our solar system. The Earth is made up largely of rock which is not that dense when compaired to the inner planets which have more nickel and iron. Go find a good solar astronomy class before try to lecture on the subject next time.

    www.starstuff.org
  • I finally got around to renting M2M last night - god what a horrible movie. "The Face" should have been "the Scarface" and it should have been made out of 100% pure Columbian white. Inside they should have found a bunch of Cuban gangsters, and maybe a high-school psychokineticist, instead of Bambi-the-space-alien.
  • A quick refresher of the chemistry of water, CO2, and life:

    Water is an excelent solvent for polar (ionic) compounds like salt. CO2 is an excellent solvent for light organic compounds. Life consists of parcels (cells, globules) of complex chemistry, packaged in a lipid (fatty acid) membrane.

    If water and liquid CO2 co-exist, they form small globules of one liquid in the other. At the interface, both polar and non-polar chemistry are possible. Lipids naturally line up at the boundary and form sheets that seal in the globules. Perhaps this is the first, crucial step towards the origin
    of cellular life.

    Maybe self-replicating chemicals already existed, but the packaging into cells was the vital step towards life as we know it. Perhaps conditions on the early Earth were cold enough for liquid CO2 to exist in some regions, and permit life to begin in this way? What a balance! Too cold and the water freezes. Too warm and the CO2 boils, and the greenhouse effect amplifies any change in insolation making the balance razor sharp.

    If life required such a careful balance of temperatures to begin, then perhaps the habitable zone is much, much narrower than most people
    imagine?
  • But the current laws of physics only apply until they are disproved or superseded. There are so many things we don't know (matter as a wave and a particle is something that hasn't been figured out yet) that to say that the physical laws currently held to be true are the be all and end all of science.
  • I think it is misleading to assume that such planets are the best place to look for life. Certainly it is the best place to look for life as we know it -- carbon based, laden with liquid water, etc. But what of silicon-based life, or interstellar life forms?

    Still, the best reason to look for planets like that is they might be good candidates for a new home when we destroy/overpopulate/get-bored-with/quarantine/etc . earth.

  • The Drake equation is calcualted by multiplying seven terms together. 3 of those may be obtained from reasonable sources in astrophysics and planetary formation research (albeit they are continually changing as we learn more!). The other 5 terms are picked essentially at random, and therefore have no meaningful value.

    And it evidently uses non-standard rules for addition, too....
    /.

  • Life in Pressure Cookers (Score:4)

    by twisty ( 179219 ) on Tuesday December 12, 2000 @05:19AM (#565710) Homepage Journal
    There are holes in this 'zone'... Those familiar with the physics of Chemistry know that water has a triple-point: south of this point, the pressure is so light that there is no liquid water... it 'camphors' or evaporates straight from solid to gas. North of that triple-point, the increasing pressure broadens the range of liquid water, as the temperatures of melting-point and boiling-point move further apart.

    So let's go back to the notion that we're not talking about extraordinary life, thriving under pressure. Let's talk worlds we can personally colonize. We really aught to be seeking small planets like ourown, but dense ones:

    Earth is the most dense planet of our system. Just divide Mass by Volume, and the greatest mean density is our own. Saturn has hte least, which may account for its lovely rings. But there are many fine balancing points working in Earth's favor:

    • High Density==needed pressure for liquid water.
    • Small Size==low gravitational mass, ==fewer sheering stresses fighting life's 'order.'
    • Proximity to Sun==dynamic energy ('chaos') for creating (mixing) and sustaining (maintaining) life.
    • Distance from the Sun==cooler order to prevent life from burning away in excessive energy.
    So earth is unique to our system in being a light-weigth pressure cooker for life. We actually have a better chance outside our own solar system, where greater planetary densities exist, if getting there can be trivialized. Then again, the technology to make insterstellar travel trivial would likely make terraforming even more trivial.

  • From a Jovian's point-of-view (Score:5)

    by Trinition ( 114758 ) on Tuesday December 12, 2000 @05:23AM (#565713) Homepage
    I don't see how a planet such as Earth could have life. Its gravity is so weak, due to its small mass it could only capture *one* moon! With such low gravity, the gaeous pressure is so low that no organism could possibly find enough nutrients at that density to sustain its life.

    Furthermore, even if it could, its body would surely explode due to the low atmospheric pressure. Or, perhaps the weight of the organism could not be suspended by the atmospheric pressure and it would crash to the center of the planet.

    There is also the thin atmosphere. The planet is small enough, but its atmosphere is a tiny shell and hasd a relatively massive solid core. That leaves little room for life to develop.

    I tell you, Earth is no more habitable to life than Mars is now ever since the Matrians turned their gas giant into a desolate rock!

  • Ever heard of spectroscopy?
  • Although the oceans shouldn't be too big - just imagine the tidal wasves :-)

    Gas giant moons would quickly become tidally locked (facing one side to the planet), so the tidal bulges produced by the planet would stay put. The only ebb-and-flow would be from solar tides.
    /.

  • The data [twisty.org] from NASA corroborates my statement... I hope your 'correction' wasn't what you learned from the 'better class' you tout... You were close, but incorrect:

    When you do the math as I suggested:
    Mercury = 5.4299e+12 kg per cubic km
    Earth = 5.5206e+12 kg per cubic km

    That's what empiral data is good for... finding facts for yourself instead of accepting a spoon-fed generalization.

  • Whoops, wrong paper. Sorry. Well, here are just the radial velocity curves [exoplanets.org].
  • Drake Equation is a telltale that no one seriously studying the chances of extraterrestrial life takes into account. It is a mass of suppositions set in algebraic form for the sake of clearity. Nothing else. Drake equation does not show any probability, it only states the relations BETWEEN probabilities to give the result of the combination of these probabilities. While you don't have data about the main probabilities, Drake Equation is as beautiful as the theory of perpetual machines. You may turn the way you like and get the best result it fits you...

    Some may argue that we have some starting data. Well I will HIGHLY DISAGREE with it. Until now astronomers are discovering more and more data that strongly influences even the first variables of Drake Equation. Speciallyon what concerns the distribution, density and nature of organic compounds in the Universe.

  • If the scenario is only slightly comparable to our own solar system, those gas giants should have heaps of lil' moons orbiting them.

    Although the oceans shouldn't be too big - just imagine the tidal wasves :-)

  • The probability of extraterrestrial life can be measured using the Drake equation. The following links have more info, including a chance to try it http://www.activemind.com/Mysterious/Topics/SETI/d rake_equation.html SEARCHING FOR OTHER WORLDS - http://instruct1.cit.cornell.edu/courses/astro101/ lec27.htm INTELLIGENT LIFE IN THE UNIVERSE http://instruct1.cit.cornell.edu/courses/astro101/ lec29.htm WHERE IS EVERYONE? http://instruct1.cit.cornell.edu/courses/astro101/ lec30.htm

  • Re:Link to paper (Score:4)

    by Cyclopatra ( 230231 ) on Tuesday December 12, 2000 @12:48AM (#565752)
    I was poking around looking for something with an intended audience somewhere between the BBC article and the paper. No real luck, but here's [aao.gov.au] the full story from the Anglo-Australian Observatory website; it's got some figures and vital statistics on the planets, as well.

    -Cyclopatra

  • The probability of extraterrestrial life can be measured using the Drake equation.

    The following links have more info, including a chance to try it

    http://www.activemind.com/Mysterious/Topics/SETI /d rake_equation.html

    SEARCHING FOR OTHER WORLDS - http://instruct1.cit.cornell.edu/courses/astro101/ lec27.htm

    INTELLIGENT LIFE IN THE UNIVERSE http://instruct1.cit.cornell.edu/courses/astro101/ lec29.htm

    WHERE IS EVERYONE? http://instruct1.cit.cornell.edu/courses/astro101/ lec30.htm

  • The other question that comes up for me is: Did earth start as a gas giant? I'm thinking that what we're living on could easily be the evaporation residue of something the size and composition of Jupiter.

    Very doubtful. The huge gravitational field associated with a giant planet such as Jupiter means that "evaporation" of the gases which make up the bulk of the planet is impossible. For smaller bodies, the more-volatile substances can escape, which is why the small moons and planets tend to be airless.

    The escape mechanism is basically this: at a given temperature, molecules of a gas have a roughly-Gaussian distribution of momentum -- and the high-speed upper "tail" of that distribution may be above escape velocity, if the planet is small enough and the gas molecule light enough. Of course, there are plenty of things which add to the molecule's momentum, in the upper regions of the atmosphere, and I won't go into those...

    But the bottom line is that the gas giants are too big to lose much of their tremendous atmospheres -- which is precisely why they're "gas" giants. I suppose a collision with a large-enough object could strip gas away, but I doubt that this is what you're looking for.

    ---

  • Enrico Fermi (created first controlled fission reaction, among other things) responded to a question like this by asking: if intelligent life exists beyond Earth, why don't we have any evidence of it yet?

    Even if you throw in very pessimistic estimates about how likely intelligent life is to evolve, and how slow and hard it is to colonize other worlds, and how few colonizable worlds there are, it is still hard to come up with numbers that don't make it likely that an intelligent species would colonize the entire galaxy within a few million years of gaining space travel.

    Imagine a race on an Earth-like planet on the other side of the galaxy develops intelligence and space flight. In our case, this took 3.5 billion years after the oceans condensed, give or take a few hundred million. So in their case imagine it took the same time, but maybe their solar system formed a percent or so closer to the beginning of the universe, about a hundred million years.

    Now imagine that our shared habitat is so rare, that planets like this can only be found at an average distance of 1,000 light years from each other (note that we've found 50 Jupiter-sized planets within 150 light years of us in only a decade of slow, crude searching). Imagine this race never figures out how to travel faster than light, and takes 1,000 years to make a hop to the next inhabited world. Imagine that successful colonies are rare and take time to develop, and so it takes 1,000 years on average before a colony launches its own colonization mission. Even at this slow pace, a million years is more than enough for a race to colonize every habitable planet in the galaxy, including ours, as the galaxy is only 100,000 light years in diameter.

    So, this race would need less than a .1 percent head start from the beginning of the universe, and they would have made it in plenty of time to colonize Earth before we started walking upright.

    So, where are they?
  • If you're going to do a simple cut-and-paste from Nick Hoffman's White Mars [latrobe.edu.au] website, you should at least have the courtesy of giving him the credit.

    Geez, you didn't even bother to edit out the line break in the final paragraph...

    ---

  • No I'm not talking about the star's wobble but about the planet's one. Planets possessing low rotation speeds and either too high or too low inclinations to the star system's eclyptic, plus a spin that changes too slow, will create serious thermodynamical conditions to the planets themselves. Such is the case of Venus for example. Or the _possible_ case of Earth during after the Permian. At such conditions the planets suffer an overheat. Venus as a 400 degrees and 90 atmospheres in its surface. Earth reached nearly 80-100 degrees inside the continent. Well Earth managed to keep life "alive" because it already had lots of water back then. But a small disbalance and you may get a "hot Mars" in place.
  • Nukes have already been used on a small scale here. Remember?

    Your statement that nuclear war "won't happen" is faith-based, maybe -- certainly there's nothing objective to assure us that it won't happen. Ever notice the willingness of some people to kill themselves in suicide-bomb attacks? To me, the possibility of a "doomsday" response by the losing side in a major war is very real. YMMV -- but reality is independent of either of our beliefs, isn't it?

    ---

  • No sweat... It happens to the best of us... My "correction correction" could have looks *so* much more suave had I correctly spelled "empirical." ;-)

    I get that a lot when I share my "Earth is Most Dense" [twisty.org] discovery... People just reactively say "How can that be? Surely someone would have taught me that in school?!" The more I see such relationships escape the public attention, the more I am prone to tackle things like Goldbach's Conjecture.

    "Curse my metal body--I wasn't fast enough!" -C3PO

  • hmm.. (Score:2)

    by radja ( 58949 )
    >The smallest of the three is an object called a "hot Jupiter" because it sits just six million kilometres from its parent star, HD179949 in the constellation Sagittarius.

    >The planet, which has a mass that is 84% of our Jupiter, orbits the star in only three days.

    hmm.. a 72 hour year?? wow.. not only is this thing hot.. it's quite fast at 4.3633 * 10^14 m/s.
    (6M km radius, assuming perfectly circular orbit). Anyone have an idea what average earthspeed around the sun is?

    //rdj
  • We have the seasons because of earth inclination. This means that because of several hundreds of kilometers (look in your old trigonometry books), a place in the North hemisphere and a the corresponding place in the South hemisphere won't have the same climate.
    OK, the ellipsoidal nature of Earth's revolution also helps but not quite much more.
    My question is that if we have Jupiter-like planets, how could they be uniformly warmed by their Sun ?
    What about their rotation, their revolution ?
    Is it sure any point of their surface would equitably benefit from enough light rays to maintain it a temperature suitable for life development ?

    --

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