New Planet May Be Able to Nurture Organisms

Originally posted by lausey
Life, as we know it, is a key point as well. It doesn't rule out the possibility of life vastly different from ours from evolving in very different environments.

Of course, life has a very good chance of evolving very differently to ours, even on a planet similar to our own.

Life as the one we have, is the only life we know of, so far. I can imagine that life can be very different, and very strange. Our DNA, a double helix, is not the only solution of the problem how to transmit information from generation to the next. Why not a single strand of information encoded in some poly-something molecule? And so on. Only the fantasy is the limit.

So we must be open to other life using other principles. But our life is so far the only one we have experionce of.

Originally posted by AThousandYoung
Is it possible that life has evolved over there which is resistant to radiation? Maybe in some kind of shielded environment?

Does anyone know how well water protects against the radiation in question? I thought that life in the seas would probably survive quite well even without earths magnetic protection or atmosphere.

Originally posted by FabianFnas
I'm not so sure that stable planetary orbits suitable for life is impossible in the Alpha Centauri system.

Two sunlike stars orbiting eachother at a distance from eachother of between 11 and 35 AU in an elliptic orbit, giving an orbital period of 80 years. A planet of the size of Earth, orbiting one of the stars at 1 AU, will be disturbed over the time of the other star, so life (as we know it) might be hard to evolve.

That problem has already been worked out, there can be totally stable orbits around either star.

Here is a link to one such effort:

http://www.solstation.com/orbits/ac-absys.htm

Originally posted by sonhouse
That problem has already been worked out, there can be totally stable orbits around either star.

Here is a link to one such effort:

http://www.solstation.com/orbits/ac-absys.htm

Of cource, theoretically there are stable orbits, but in reality they are highly unlikely in the habitable zone. Remember the planet has to be in the right distance from the star(s) in order to have a temp suitable for life.

Originally posted by FabianFnas
Of cource, theoretically there are stable orbits, but in reality they are highly unlikely in the habitable zone. Remember the planet has to be in the right distance from the star(s) in order to have a temp suitable for life.

Those two stars are roughly the size and luminosity of our sun so the Goldilocks zone would be roughly at 1 AU and that is a stable orbital distance for those two stars.

Originally posted by sonhouse
Those two stars are roughly the size and luminosity of our sun so the Goldilocks zone would be roughly at 1 AU and that is a stable orbital distance for those two stars.

I say there are not a stable orbit at roughly 1 AU of one of the stars, when the two stars is orbiting eachother with such elliptical orbits. Not a stable orbit for so long period of time needed to establish life on the planet. I say, highly improbable. Takes a divine interaction for this to happen.

Originally posted by FabianFnas
I say there are not a stable orbit at roughly 1 AU of one of the stars, when the two stars is orbiting eachother with such elliptical orbits. Not a stable orbit for so long period of time needed to establish life on the planet. I say, highly improbable. Takes a divine interaction for this to happen.

Yeah, just ask Kelly🙂
Seriously, there was an article in Scientific American a few years ago about that subject and the conclusion was there were stable orbits possible. Whether there are actual planets at the sweet spots is another issue.

Here is one link and comment about this issue:

From Solstation;
http://www.solstation.com/stars/alp-cent3.htm

In a binary system, a planet must not be located too far away from its "home" star or its orbit will be unstable. If that distance exceeds about one fifth of the closest approach of the other star, then the gravitational pull of that second star can disrupt the orbit of the planet. Recent numerical integrations, however, suggest that stable planetary orbits exist: within three AUs (four AUs for retrograde orbits) of either Alpha Centauri A or B in the plane of the binary's orbit; only as far as 0.23 AU for 90-degree inclined orbits; and beyond 70 AUs for planets circling both stars (Weigert and Holman, 1997). Hence, under optimal conditions, either Alpha Centauri A and B could hold four inner rocky planets like the Solar System: Mercury (0.4 AU), Venus (0.7 AU), Earth (1 AU) and Mars (1.5 AUs).
So planets could exist out to 3 AU (4 AU for planets going 'backwards' compared to the star, which might be more common that previously thought).