Originally Posted by Fantasus
While most "ufology" is not real science, the numbers of observations of exoplanets grows fast. That I see as great scientific progress of this age, and may lead to some new insights about the challenges for life on earth nas well as beyond.
Although almost all of the so far discovered exo-planets do not appear Earth-like, this does not automatically exclude life or evolution upon them. Life, if it exists on any of them, will not, however, be like anything we can imagine.
The main quest here is to find an Earth-like planet in another star system. This does not occlude the moons of some of the many Jupiter sized planets (or larger) already discovered, either. We simply are currently unable to discern what moons, if any, might currently exist around any of these exo-planets. There could be literally thousands of moons around the already located objects. If the example of our own Solar System is common among other solar systems, there could be a ten to hundred fold increase in potential life supporting surfaces as well.
The most interesting and conclusive aspect will come from the discovery of life on another body within our own Solar System. Such information will practically guarantee fecundity for many bodies in other star systems. And with the discovery of life on several other locations within our Solar System, this will increase exponentially the likelihood of many more life inhabiting planets existing out there.
What is definitely known is that any planet that humans could comfortably exist on should have conditions not very different from our own planet. Gravity, oxygen, temperature and liquid water being absolute musts. However, it is not very likely that such a planet would exist without life already having taken hold upon it. Our biggest problem might come from the microbial forms of life on any exo-planet. Especially, since we would have absolutely no immunity to it. And it is most likely that the most common forms of life will exist at the microbial level. Immunization specialists will be in great demand.