我在Twitter上关注这个江南体育网页版地球科学家伙。这家伙爱地球科学和每隔一天他似江南体育网页版乎推寻找新的“可居住的太阳系外行星”。I never thought about it until today, but I sudddenly realized a lot of factors must go into making a planet inhabitable other than just the ones that come to mind like having oxygen, the right temperature, and so on. So my question is, what makes a planet inhabitable? Also, is there an official criteria? I don't see how this guy could say we have $x$ number of official inhabitable exoplanets unless there was such a standard. Note: This question seems to intersect Biology, Astronomy, and Earth Science Exchanges. I picked Earth Science because defining characteristics are all properties of earth and earth scientists probably know most about them.