Adam's new book, Light of the Stars: Alien Worlds and the Fate of the Earth ... Adam: Climate change is a civilizational inevitability ... How many planets are in our galaxy? Guess again. It’s more than that. ... How pessimists about the existence of extraterrestrial life became optimists ... Why haven't we heard from any aliens? ... Does fighting climate change require spiritual change? ... Why the Gaia hypothesis isn't new-age hooey ... The theoretical archaeology of exo-civilizations ...