The Andromeda galaxy is the closest big galaxy to our Milky Way. At 2.5 million light-years, it's the most distant thing you can see with the eye alone.
The fossil remains of a sea cow from the Miocene Period reveal bite marks that suggest it was attacked by a crocodile and subsequently scavenged by sharks.
Landslide-triggered tsunamis due to melting glaciers and permafrost are becoming more common with global warming. Read more about Alaska and Greenland.
Astronomers with the Event Horizon Telescope Collaboration have developed a new technique that will produce direct black hole images with 50% better resolution.