Astrobiology is an interdisciplinary field, combining aspects of astronomy, biology and geology, which considers the question of whether extraterrestrial life exists and if so, then what are its origin, distribution, and evolution.
Some major astrobiological research topics include:
-What is life?
-How did life arise on Earth?
-What kind of environments can life tolerate?
-Can we detect life on other planets?
When looking for life on other planets, some simplifying assumptions are useful to reduce the size of the task of astrobiologists. One is to assume that the vast majority of life-forms in our galaxy are based on carbon chemistries, as are all life-forms on Earth. While it is possible that non carbon-based life exists, carbon is well known for the unusually wide variety of molecules that can be formed around it.
The presence of liquid water is also a useful assumption, as it is a common molecule and provides an excellent environment for the formation of complicated carbon-based molecules that could eventually lead to the emergence of life.
A third assumption is to focus on Sun-like stars. Very big stars have relatively short lifetimes, meaning that life would not likely have time to evolve on planets orbiting them. Very small stars provide so little heat and warmth that only planets in very close orbits around them would not be frozen solid, and in such close orbits these planets would be tidally "locked" to the star, with one side of the planet perpetually baked and the other perpetually frozen.
About 10% of the stars in our galaxy are Sun-like, and there are about a thousand such stars within 100 light-years of our Sun. These stars would be useful primary targets for interstellar listening. However, we only know of one planet where life exists, our own. There is no way to know if any of the simplifying assumptions are correct.
And there is absolutely nothing that says anything about what these other life forms look like,if they exist at all.I keep hearing about Grays,Blonds,lizard alien humanoides on this and other forums and all I can think is --kids have a wonderful imagination.
Full Version: Astrobiology.
Unexplained Mysteries Discussion Forums > Unexplained Mysteries > Extraterrestrial Life & The UFO Phenomenon
QUOTE(hazzard @ Dec 18 2005, 07:11 AM) [snapback]981099[/snapback]
When looking for life in other planets, some simplifying assumptions are useful to reduce the size of the task of astrobiologists. One is to assume that the vast majority of life-forms in our galaxy are based on carbon chemistries, as are all life-forms on Earth. While it is possible that non carbon-based life exists, carbon is well known for the unusually wide variety of molecules that can be formed around it.
Scientists are now questioning whether lifeforms could exist that are silicon-based.
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The presence of liquid water is also a useful assumption, as it is a common molecule and provides an excellent environment for the formation of complicated carbon-based molecules that could eventually lead to the emergence of life.
Yes, if you want to find life, water is a good place to start.
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A third assumption is to focus on Sun-like stars. Very big stars have relatively short lifetimes, meaning that life would not likely have time to evolve on planets orbiting them. Very small stars provide so little heat and warmth that only planets in very close orbits around them would not be frozen solid, and in such close orbits these planets would be tidally "locked" to the star, with one side of the planet perpetually baked and the other perpetually frozen.
Yes, exactly.
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I keep hearing about Grays,Blonds,lizard alien humanoides on this and other forums and all I can think is --kids have a wonderful imagination.
One can't help but think that. It's the easiest explanation...
Recently, I came across this rather interesting article. Granted, it's doubtful that there'd be Star Trek type aliens inhabiting other planets, but bi-lateral beings that are bi or quadra pedial does seem to be likely.
When it comes to aliens, though...there's just no way to really know!
When it comes to aliens, though...there's just no way to really know!
hey mind freak love the new sig it has more effect now 
Hendrix has spoken (just trying it on)
Hendrix has spoken (just trying it on)
I liked the last part Lilly.
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Could they be humanoid within a modern TV budget? Definitely.
I also liked the paragraph concluding what you might "end up with" given the author's parameters:
It certainly does pique one's imagination!
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What do we get? Something at least partly upright, with jointed limbs matched right-to-left, some sort of grasping/manipulating hands and a head probably moved more above than in front of the body. A couple of eyes (single lens, which is a better system than multiple lenses [compound eyes] if you've got the room), a mouth, some sort of nose, possibly ears. Humanoid? Maybe. If velociraptors had had a chance to keep evolving, would their intelligent descendants be humanoid? Depends on how you define "humanoid."
It certainly does pique one's imagination!
I've always thought that the majority of extraterrestrial life forms would fall outside of the accepted criteria under which astrobiologists exclusively base their searches on.
QUOTE(falseprophet15 @ Dec 19 2005, 10:59 AM) [snapback]982529[/snapback]
I've always thought that the majority of extraterrestrial life forms would fall outside of the accepted criteria under which astrobiologists exclusively base their searches on.
More than likely. A LOT of people EXPECT that life on another planet would be similiar to life on Earth...carbon based, oxygen breathing, etc. They don't consider that sentient (or otherwise) life might prosper on frozen worlds, or Venus like ovens, or even gas giants. The point is, we just don't know what forms life MIGHT take elsewhere or what environment they would find hospitable. I suspect that there is more than one species that would consider our environment to be deadly.
QUOTE(Kallen @ Dec 19 2005, 02:36 PM) [snapback]982788[/snapback]
More than likely. A LOT of people EXPECT that life on another planet would be similiar to life on Earth...carbon based, oxygen breathing, etc. They don't consider that sentient (or otherwise) life might prosper on frozen worlds, or Venus like ovens, or even gas giants. The point is, we just don't know what forms life MIGHT take elsewhere or what environment they would find hospitable. I suspect that there is more than one species that would consider our environment to be deadly.
I like that, nicely said, I agree...
QUOTE(Kallen @ Dec 20 2005, 05:36 AM) [snapback]982788[/snapback]
I suspect that there is more than one species that would consider our environment to be deadly.
Yes! This is true! We seem to expel great doses of "Methane Gas" which must mean that we are full of something that is not desirable to either our atmosphere, or incoming visitors for that matter. Could it be that this is the reason that we don't have direct contact with these visitors, because of all the excremental influence and talk?
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What do we get? Something at least partly upright, with jointed limbs matched right-to-left, some sort of grasping/manipulating hands and a head probably moved more above than in front of the body. A couple of eyes (single lens, which is a better system than multiple lenses [compound eyes] if you've got the room), a mouth, some sort of nose, possibly ears. Humanoid? Maybe. If velociraptors had had a chance to keep evolving, would their intelligent descendants be humanoid? Depends on how you define "humanoid."
That author gets no points for creativity. First off, why would intelligent alien life necessarily develop eyes, period? And his argument against multi-legged intelligent life only makes sense if you assume that the animal life will evolve on a basic skeletal form with four limbs, which you can see in virtually all vertebrates. What if the original vertebrate was an eight-limbed creature?
QUOTE(I AAAM @ Dec 20 2005, 01:16 AM) [snapback]983286[/snapback]
We seem to expel great doses of "Methane Gas" which must mean that we are full of something that is not desirable to either our atmosphere, or incoming visitors for that matter. Could it be that this is the reason that we don't have direct contact with these visitors,
Yes it is possible,but the more probable explanation for any ETI neighbors not stopping by is the enormous (to say the least) distance between the stars.
QUOTE(hazzard @ Dec 20 2005, 09:55 PM) [snapback]983976[/snapback]
Yes it is possible,but the more probable explanation for any ETI neighbors not stopping by is the enormous (to say the least) distance between the stars.
Well! What can I say? "I AM" beyond words to your reply!
IGNORANCE IS BLISS.
QUOTE(I AAAM @ Dec 19 2005, 07:16 PM) [snapback]983286[/snapback]
Yes! This is true! We seem to expel great doses of "Methane Gas" which must mean that we are full of something that is not desirable to either our atmosphere, or incoming visitors for that matter. Could it be that this is the reason that we don't have direct contact with these visitors, because of all the excremental influence and talk?
Sorry guys...I KNEW I shouldn't have eaten those tacos last week...now I gone and skeered off E.T.
QUOTE(Kallen @ Dec 21 2005, 04:33 AM) [snapback]985278[/snapback]
Sorry guys...I KNEW I shouldn't have eaten those tacos last week...now I gone and skeered off E.T.
I'm holding you and every cow on the planet personally responsible.
And if I were you I would ducktape my butt before going to bed,you know about
the alien-cow relationship ,right.
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