The strange behavior of Tabby’s Star, or KIC 8462852, has inspired modern astronomy’s wildest guessing game, with explanations ranging from aliens to sunspots. Writer Stephen Petranek got Tabby herself to assess the competing ideas.

People are obsessed with Mars. But … why? Two confessed super-fans, Andy Weir, author of “The Martian,” and Stephen Petranek, author of “How We’ll Live on Mars,” share thoughts on why being Mars-mad is a reasonable state of mind.

Author Stephen Petranek makes the case that humans will live on Mars in the not-too-distant future. He explains how and when this might happen — and what risks those who head there first might face.

Humans are off to live on Mars. At least, that’s the case journalist Stephen Petranek makes in his TED Book, “How We’ll Live on Mars.” According to Petranek, the move is no less than an “essential back-up plan for humanity.” Here, he shares just some of the factors those who make the first trip will have to manage.