NASA's Stardust-NExT mission took this image of comet Tempel 1 at 8:39 p.m. PST (11:39 p.m. EST) on Feb 14, 2011 for this cool space wallpaper. The comet was first visited by NASA's Deep Impact ...

In early 2015, Comet Lovejoy zoomed toward the outer solar system with a stunning starry background. Highlights of the beautiful backdrop are the bright bluish Phi Persei near the bottom of the ...

A newly discovered green comet is zipping by Earth and is now visible for the first time since before Galileo invented his telescope.