The exoplanet HD 20794d swoops in and out of its habitable zone every few hundred days, making for an extreme climate.

NASA has explored the space beyond Earth and our solar system with spacecraft like Voyagers 1 and 2, and how we’ve discovered ...

Early sci-fi exoplanets were often simple Earth-like worlds, but as science advanced, so did their realism. From the desert planet Arrakis in Dune to the bizarre gas giant moons in Avatar, fictional ...

"We are literally mapping the entire celestial sky in 102 infrared colors for the first time in humanity's history." ...

But how well do you really know our planetary neighbor? This quiz of 15 questions will test your knowledge of Mars' size, surface and history, as well as scientists' attempts to study it. Remember to ...