Title Text:The Earth is, on average, located in the habitable zone, but at any given time it has a certain probability of being outside it, which is why life exists on Earth but is mortal. Origin:https://xkcd.com/2709/ https://www.explainxkcd.com/wiki/index.php/2709:_Solar_System_Model 太阳系模型 平均而言，地球位于宜居带，但地球随时都有一定的概率处于宜居带之外，这就是为什么地球上存在生命，但总有一死。 http://xkcd.in/comic?lg=cn&id=2709…