Have you ever wondered what life on other planets would look like? There are plenty of science fiction films and literature that show some of the possibilities that their creators have come up with. However, it is most likely that these are not accurate. In fact, there is a fairly high chance that any alien life that we discover will be mostly microbes. Of course it is impossible to say this for certain when no life on other planets has ever been observed. Our only source for what life can possibly look like is what exists, or has existed, on Earth itself. Of course one might ask, “If Earth has multi-celled organisms, why wouldn’t other inhabited planets have them?” However, for most of our planet’s history, multi-celled organisms did not exist. If one were to travel back to any random time in Earth’s history, that time is most likely to be one where there is only microbial life. Also, in the distant future, when life on Earth is dying out, microbes are likely to last the longest. In fact, there are some microbes that are quite good at surviving in extreme environments. Overall, if life on other planets is anything like life on Earth, then we can expect to find populations of microbes in the vast majority of cases. Yet who says that life on other planets will be anything like life on Earth? While there are bound to be at least a few similarities (so microbes are still likely), since chemistry is the same anywhere in the universe, it is impossible for us, given our limited sample of possible lifeforms, to come up with every possible type of life. So there are bound to be aspects of life on other planets that we would have never seen coming, even if that life is still composed of single-celled organisms.

The fact that microbial life is most likely to be the most common form of life on other planets poses a major problem: How does one find evidence of the existence of something so tiny on a planet so far away? To come up with a feasible answer will require more research, and a deeper understanding of the effects that microbes can have on a planet.