Comets: News on Sightings, Missions and Encounters

'Oumuamua is long gone, but it's still leaving scientists guessing. A new explanation proposes that the strange object was a "monstrous fluffy dust aggregate" produced by a busted-up comet.

The dense atmosphere roiling on Saturn's largest moon, Titan, may come from organic material baking in the moon's interior.

Names matter, even when they're temporary nicknames for objects 4.1 billion miles (6.6 billion kilometers) away from Earth.

Just in time for Christmas, the latest apparition of a comet shines like a beautiful ornament in the sky — a delightful green-shrouded treat for amateurs and scientists alike.

You can expect a ghostly green blob to grow brighter in the sky near Orion in the coming days, as Comet 46P/Wirtanen makes its closest approach to the Earth in 20 years this weekend.

The Geminid meteor shower will provide a shining backdrop for the approach of Comet 46P/Wirtanen on Thursday (Dec. 13), shortly before the object's closest approach to Earth in 20 years.

See skywatcher photos of the bright-green, naked-eye Comet 46P/Wirtanen during its close approach to Earth in December 2018.

As you read this, a small comet is on its way toward making a very close pass of Earth in mid-December — its best appearance over a period of four centuries.

The source of some of Earth's first water may be gas left over from the sun's birth.

Scientists are one step closer to understanding why some comets have strange dust bands in their tails. The main culprit in this cosmic mystery? Our own sun.

A year ago, astronauts spotted a strange object barreling through our solar system on a very weird path — the first discovery of an interstellar object, now called 'Oumuamua.

Ever since astronomers first spotted their first-ever object from beyond our solar system, it has offered more questions than answers — what is it? Where did it come from? Why is it so darn weird?

This month, a periodically returning comet designated 21P/Giacobini-Zinner is bright enough to be seen in binoculars and small telescopes. Here's how to track it.

See photos of Comet 21P/Giacobini-Zinner and the naked-eye comet 46P/Wirtanen, which will swing around the sun in September and December.