The Universe

The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define

This year, from Earth’s perspective, Saturn’s rings will appear nearly edge on, making them almost invisible

A little-known chapter of the Hubble Space Telescope’s history is a reminder of the risks of looking at the sun

The heavens will provide a bounty of viewing treasures in the coming year

The familiar zodiac constellations are defined by Earth’s motion around the sun, but they don’t define your fate

Twenty years ago today a magnetar’s epic tantrum made our planet ring like a bell from tens of thousands of light-years away

With billions of stars in the Milky Way, some nomenclature standardization is necessary

The celestial equivalent to latitude and longitude lets astronomers find their way across the heavens

Barnard 68 is often mistaken for a hole in space, but it’s actually a dense, opaque cloud of dust—for now

“Twilight rays” are but one of several viewing treats for the liminal time between day and night

Called Olbers’ paradox, the seemingly simple mystery of the sky’s darkness is something that stumped astronomers for centuries

Finding a perfect sphere is actually pretty difficult