Retrograde Rock "Niku" Defies Orbital Trend
The discovery of trans-Neptunian object 2011 KT19 in a strange orbit deepens a key mystery in the outer solar system.
Explore the Night with Bob King
Comet PanSTARRS 2016's Historic Flyby of Earth
Not one, but two, possibly related comets will make exceptionally close flybys of Earth on March 21–22. Here's what we know and a guide on how to see them.