Yep! And more specifically, if we found a planet that had an atmosphere with O2 in it, that would be highly indicative of life. Although it's not the only opti

Yep! And more specifically, if we found a planet that had an atmosphere with O2 in it, that would be highly indicative of life. Although it's not the only option, O2 is pretty reactive, and you need a constant O2-producing force to maintain it. An O2-producing force would be something like plants or some life that is creating hydrocarbons from CO2 and H2O.