Earth is the only planet that can support life?

Answer 1

So far, no signs of life have been found on other planets. The best that scientists can do is speculate on whether it does or has existed, based on conditions and estimated conditions of other planets and exoplanets. There is a good chance that other planets around other stars (exoplanets) can support some kind of life, if the conditions are right.

Answer 2

As far as we know, Earth is the only planet that currently supports life. However, life is very durable and recent studies have indicated that it can take forms previously unexpected within the scientific community. It is likely that there is, at least, microbial life elsewhere (or, in some cases, was in the past), and there are a number of probable candidates for where they may be found. To date, we have not definitively found life elsewhere in the universe; but we are actively searching.