The UniverseFebruary 2, 2024
Where Does Outer Space Begin?
The popular limit of a 100-kilometer altitude for the edge of space should probably be adjusted down to 80 km
The Universe
Every Friday, astronomer Phil Plait brings the universe over your head down to Earth.
The UniverseJanuary 26, 2024
How Far Away Is the Horizon?
The edge of the world is closer than you think, and simple geometry proves it
The UniverseJanuary 19, 2024
This Nearby Brown Dwarf May Have Auroras—And a Moon, Too
Glowing methane on a brown dwarf dozens of light-years from Earth may signal the presence of a large lunar companion
The UniverseJanuary 12, 2024
Earth’s Wobble Wreaks Havoc on Astronomers—And Astrologers, Too
Our planet’s precession is scarcely noticeable during anyone’s lifetime, but across history, it has had enormous effects
The UniverseJanuary 5, 2024
Sky Spectacles to Watch in 2024
Here’s a calendar of cosmic events to keep your eyes on in the coming year