Cover: An artist's rendition of the range of issues and environments addressed by astrobiologists, as described in The Astrobiology Primer v2.0, in this issue. This picture depicts a rover on an alien planet, created by merging imagery from multiple astrobiologically relevant locations from across the Solar System. Image by Aaron Gronstal, based on a concept by Shawn Domagal-Goldman. Sources for this include pictures of a sulfur-coated glacier in the Canadian High Arctic and hot springs in Yellowstone National Park, both sites where astrobiologists study life in extreme environments (photos by Katherine Wright); a planetary-exploration rover (image credit: NASA); an image of a gas giant (Saturn), around which potentially habitable moons exist; a haze-rich atmosphere, which may have been present on early Earth; and a star-filled sky in which many extrasolar planets are to be found and eventually characterized.