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zrice03
2004-May-31, 11:27 PM
I was reading recently how, in computer simulations, it is relatively easy to create Earth-like planets in Earth-like orbits. To make it habitable, there is also usually a Jupiter-like planet further out that kicks out much of the rest of the debris so that the planet isn't continuously pelted.

The thing is, we know from discovering planets around other stars that Jupiter-like planets can migrate inwards. Doing this would probably eject any inner planets that were there.

So: If there is no Jupiter-like planet, the planet is likely hit by comets and asteroids and it becomes impossible for life to form, or there is a Jupiter-like planet and it migrates inward, ejects any life-bearing worlds, and kill any life that was there.

Granted, not all cases are like this (we're still here), but I think that, given this, life may be quite rare.

imported_Ziggy
2004-Jun-01, 12:44 AM
Your right. Planets with life are rare. By our standerds. I think the number is one in every 226 solar systems have a planet with an active ecosystem. That means currentlly, there are about 4,000,000,000 planets with complex ecosystems active in our galaxy. Add moons and I'd say the final number of planets and moons with a complex ecosystem active in our galaxy right now is somewhere between 4,250,000,000 and 5,000,000,000 (the actual numbers makes it look very impressive :D ). Those with intelligent life, just type in your own factors for the drake equation.

zrice03
2004-Jun-01, 01:39 AM
1 of 226? That's an awfully precise number.

Deep_Eye
2004-Jun-01, 02:22 AM
Really...thats what I thought too. I think 226 is getting very close (if not past) the actual number of extra solar planets discovered period-with active ecosystems or not.

zrice03
2004-Jun-01, 05:33 AM
I don't think any of the planets discovered so far have biospheres on them. They are all Jupiter-like and very few are actually in the life-habitable zone, where liquid water is possible.

Deep_Eye
2004-Jun-01, 01:15 PM
Thats what I had thought too. If a planet with an ecosystem had been discovered-we'd have heard a lot more about it-and would still be hearing about it.

John L
2004-Jun-01, 04:26 PM
Our best detection method is radial velocity, measuring the motion of the parent star caused by the presence of a planet. By its very nature it is skewed to discovering high mass planets (greater than 1/2 Jupiter mass) and planets in close orbits. To discover a planet definitively using this method you need to observe it for more than one full orbit. Therefore, to discover our Juipter you would have to observe the motion of the Sun for 11.9 years just to get one full orbit's data. Since there is also Saturn, Uranus, Neptune, and the smaller planets you'd want to probably go to two full orbits to be sure. That's 24 years of observing one star to find our solar system or its equivalent.

It will take a very long baseline interferometry setup to detect Earth and be able to measure the atmospheric composition to identify a habitable world. We're still about a decade or two from having that system up and running.

Deep_Eye
2004-Jun-01, 04:34 PM
Really? I thought that they had methods in which they could detect types of chemical compounds in a planet's atmosphere. Hence, certain compounds are more necessary for life than others.

GOURDHEAD
2004-Jun-01, 05:49 PM
If a planet with an ecosystem had been discovered-we'd have heard a lot more about it-and would still be hearing about it.

It has, we did, we are. It's earth; it's the one in the one in N that we know about. It's reasonable to assume, though we have no proof, that where there are gas giants, there are terrestrials. Also, it would not be surprising to find large moons around some of the giants that could support life. I expect that we'll find life on Europa, Ganymede, Callisto, and Titan.

Deep_Eye
2004-Jun-01, 06:27 PM
Its Europa that is thought to have water under its surface, right?

zrice03
2004-Jun-01, 07:12 PM
Yep. Europa is likely to have an ocean underneath its icy surface. Ganymede and Callisto might also have subsurface liquid water.

Deep_Eye
2004-Jun-01, 07:22 PM
I know that there is a planned mission to Europa sometime in the future, but what about the other moons? And all those that you metioned are moons of Jupiter right?

StarLab
2004-Jun-01, 07:22 PM
Europa is likely to have an ocean underneath its icy surface. Ganymede and Callisto might also have subsurface liquid water.
In that case, in the future, when the sun begins to redden and gt bigger, why can't we just move to Jove, then, call it our 'new sun' and call Europe, Ganymede and Callisto new Earth 1, new earth 2 and new earth 3?

Deep_Eye
2004-Jun-01, 07:30 PM
Because even though they may have water under the surface, the surface temperatures are still too cold to contain it on the surface. Not only that, but I'm sure may of the things we need and are used to just are pheasible for those moons. And I don't think the human population could fit on them either, especially by the time the sun is expanding.

antoniseb
2004-Jun-07, 04:50 PM
Originally posted by Deep_Eye@Jun 1 2004, 07:30 PM
I don't think the human population could fit on them either, especially by the time the sun is expanding.
The human population today could easily fit on any one of the icy moons of Jupiter, but they'd have to build some deep structures to avoid the radiation.

If you are looking for a very stable place to live, perhaps a ring-world around a medium sized red dwarf would be best. There's plenty of them nearby. Maybe Barnard's star would be a good choice.

imported_Ziggy
2004-Jun-10, 04:04 PM
The 1 in 226 systems thing used our solar system as a model. Can't remember who did the estimate though.

John L
2004-Jun-10, 04:20 PM
Originally posted by Deep Eye Sez+--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Deep Eye Sez)</td></tr><tr><td id='QUOTE'>Really? I thought that they had methods in which they could detect types of chemical compounds in a planet&#39;s atmosphere. Hence, certain compounds are more necessary for life than others.[/b] IF the planet passes directly in front of its parent star relative to Earth, and if we have a good telescope with a spectrometer hooked up we can detect the change in absorption lines in the light of the star and determine what elements are in the atmosphere of the breifly intervening planet. The Hubble Space Telescope (http://hubblesite.org/newscenter/newsdesk/archive/releases/2001/38/text/) took the measurements you&#39;re thinking about.

<!--QuoteBegin-Deep Eye also Sez
I know that there is a planned mission to Europa sometime in the future, but what about the other moons? And all those that you metioned are moons of Jupiter right?[/quote] The Jupiter Icy Moons Orbiter (JIMO) (http://www.jpl.nasa.gov/jimo/) is the current planned mission to Europa, Ganymede, and Callisto. There are ideas for landers, drillers, and even submersibles for Europa, but JIMO is the only one that has the go ahead and funding that I know of.

Does anyone know where that 1 in 226 number comes from? Is that systems with any planets? It must be since the only system that we know has life is one - ours.

paultrr
2004-Jun-12, 09:09 AM
No planets smaller than Jupter size have been discovered. Jupter, as far as we know does not have an active biosphere in the sence that earth does. However, most of the building blocks for an active biosphere have been discovered out there. That translates to other worlds with a biosphere being possible. Now as to odds, I&#39;d be surprized if life as we know it was not rare. Given there are many possibilities on how a system could have planetary orbits and given the variance in stars alone I suspect Jupter size planets to be the norm and earth like planets the exception to begin with. In our system we have two known planets with water: Earth and Mars. We have a third that we can speculate from current conditions had water and experienced a runnaway greenhouse effect, Venus. We have two Moons out there that seem to have indications they contain some form of a sea under their frozen surface. Now sea here could be any liguid, not just water. So in all we have in our own system two out of nine planets with water. Only one is presently known to actually harbor life. If every star has some planets, and the common fact is only a few have the right stuff then that one out of nine fact might also apply to other systems where we have 1 out of nine stars having the right condition. But of those one could expect that only a few are just right enough themselves.

nexceo
2004-Jun-12, 10:59 PM
[FONT=Arial][SIZE=7][COLOR=purple][B][I]there seems to be quite the misconception that there is something out there besides us, yet there hasn&#39;t been any planets as small as the earth found as of yet, and there are other conditions and needs that need to be met before a place is able to sustain life. distance from its home star, size, gravity, space, other planetery weather conditions, such as volcanism and tectonic activity. other things having to do with the planet and it surroundins such as population, nearby cosmic activity, and if the simple parts of survival are present, such as water, and if the living things are able to survive as long as it takes to "evolve" to its surroundings. Life span, cellular stucture, what its basic structure is made of, and to survive there are quite a few laws that are just untouchable when it comes to life away from the life that the earth sustains. these laws are the laws of physics, and other laws of survival. one of which is the law which states that a civilization, no matter how advanced, must be able to grow, multiply, and die in a timely enough manner so that planetary and cosmic cataclysms that tend to occur randomly and natually may not interfere with the survival and growth of the civilization. to think that there is something else other there beyond the human race is simply stupidity, in that there is no reason for anything else to be out there. if there were to be something else out there, then it would be beyond our imaginations to even guess how it would look, communicate with others like it, and survive on it&#39;s home planet.

GOURDHEAD
2004-Jun-13, 07:32 PM
To think that there is something else other there beyond the human race is simply stupidity, in that there is no reason for anything else to be out there . If there were to be something else out there, then it would be beyond our imaginations to even guess how it would look, communicate with others like it, and survive on it&#39;s home planet.

That&#39;s an extremely strong and unimaginative assertion. Some other thoughts to ponder are:
1. We exist
2. Carbon in water works lotsa magic.
3. Carbon and water have been observed spectroscopically to be plentiful
throughout the universe.
4. Nature allows earthlike planets to form around sunlike stars.
5. Nature allows jovianlike planets to form with satellites capable of hosting
oceans.
6. Gravitational flexing and remnant radioactive isotopes are sufficient energy
sources to drive living organisms (extrapolated from the heat observed at Io
and oceanic thermal vents on earth)
7. There are many types of living organisms on earth and varied environments in
which they prosper.
8. Life either starts spontaneously from chemical affinities and juxtaposition
fortuities (my choice) or by an edict (or edit) from God.
9. The mechanics of panspermia are logical and to a minimal degree
demonstrated by the finding of Martian meterorites on earth.

My reveling in the stupidity you assert leads me to believe that life is as likely throughout the universe as is the likelyhood that water, in its liquid form, will run downhill. Intelligence will occur because of its survival value. Those possessing it will tend to alter the universe to suit their purposes which may not necessarily be the same as ours. We must be ready to and capable of dealing with them to our mutual benefit&#33;&#33;&#33;

Cambo
2004-Jun-14, 11:49 AM
As an aside,
On another forum about aquariums there was a thread about blue/green algae, it&#39;s been around for a long, long time - millions of years. It requries warm, still water and food.
Who&#39;s to say blue/green algae has not evolved into a creature that warms the water (green house effect), dams rivers (slows water into still bodies) and supplies food (phosphate run off from farming, sewerage pumped into the rivers to name two) so that it may continue to survive?
Sounds a bit "out there" but life exists, why? Who knows&#33;
If blue/green algae can (possibly) evolve into what exists here today who&#39;s to say or limit what "life" is. Life will probably be found everywhere. Not next door because the universe by its very nature is big but in the big scheme of things it could be seen as being everywhere.
So the answer to the big question of
"The universe life and everything"
is not 42 or an experiment conducted by white mice but

To help blue/green algae survive by terra forming this planet into a more habitable planet for it.

BlackTearsofapril
2004-Jun-14, 08:52 PM
To think that there is something else other there beyond the human race is simply stupidity, in that there is no reason for anything else to be out there . If there were to be something else out there, then it would be beyond our imaginations to even guess how it would look, communicate with others like it, and survive on it&#39;s home planet.


That there sir, is a mathematical impossibility. THINK for a seccond. How could it be, in the entire UNIVERSE that not a single other planet had any lifeforms at all? Water, oxegen, carbon dioxide, and the other elements needed to sustain life are plentiful in all reaches of the universe, and can therefore sustain life, therefore, the life would flourish and evolve like all the living things here on earth. So, we could not be the only animals with superior minds in the universe. To think that we are the only ones is not only egotistical, it is totally and utterly pompous as well. (Not to insult anyone, I just think that this type of thinking is very "boxed" and has no reason behind it.)

Our planet was created by the occurence of many stellar events succesivly. First, it is theorised, that a nova or supernova blew out all the surounding dust, and then created a stable environment. Tons of these happen every day, and you cannot possibly say that none of them have ever in the history of the universe created something like us.

Greg
2004-Jun-20, 03:48 AM
The Drake equation should become more precise as we begin to digest the data coming in from the infrared observatory. The first few studies of stellar nurseries found that the galaxy is surprisingly active in forming new stars and that the vast majority of observed nascent stars had protoplanetary discs, many more than expected. This evidence suggests that most stars probably have planets, at least of the gas giant variety. The reason that extreme systems are being found by the wobble method is that it&#39;s threshold of detection is still relatively low. Therefore it is most likely to only find large planets in close orbits. Considering that and the above information aboout the frequency of planetary discs, it is reasonable to assume that most solar systems are more like ours than are unlike ours.