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Comets

Comets are remnants from the early days of the solar system, billions of years ago. Primarily made of ice and dust, these "dirty snowballs" orbit the sun and in habit the Oort cloud, an area in the outskirts of the solar system beyond Pluto. As comets approach the inner solar system, solar wind from the sun can sweep dust back into a long tail. When these comets are close enough to Earth, they can appear as dazzling objects in the night sky. Space probes from Earth have visited several comets to learn more about their composition. Learn more about comets, icy wanderers in the solar system.

Related Topics: Asteroids, Meteors, Shooting Stars and Fireballs, Rosetta Spacecraft, Stargazer Photos 

Latest Updates

The Solar and Heliospheric Observatory (SOHO) observed a comet dive directly into the sun on Aug. 15, 2019.

A Doomed Comet Just Fell Into the Sun. Here's the Video.

By Chelsea Gohd

The Solar and Heliospheric Observatory (SOHO) observed a comet diving directly into the sun yesterday (Aug. 15).

A chunk of orbiting debris (circled) is visible in this view of Comet 67P/Churyumov-Gerasimenko taken by Europe’s Rosetta spacecraft in October 2015. Spanish astrophotographer Jacint Roger noticed the object in 2019, after going through Rosetta archival photos.

Meet 'Churymoon'! Photographer Spots Tiny Moon in 2015 Rosetta Comet Photos

By Mike Wall

Europe's Rosetta spacecraft wasn't the only object circling Comet 67P/Churyumov-Gerasimenko back in 2015.

A graphic of the spacecraft's course to intercept the comet as it enters the inner solar system.

A Triple-Threat 'Comet Interceptor' Could Explore an Undiscovered Space Object

By Passant Rabie

ESA plans to intercept a comet entering our solar system

New research offers insight into how much of Earth's water came from long-ago comets.

How Did Earth Get Its Water? Scientists Now Look to 'Hyperactive' Comets for Clues

By Elizabeth Howell

Fresh observations of Comet 46P/Wirtanen, which swung by Earth in December 2018, suggest that more of Earth's water came from comets than previous studies suggested.

Every comet is unique, and its composition and location in space dictate whether it will shine spectacularly as it passes Earth or if it will fizzle out.

When Will We See Another Bright Comet?

By Joe Rao

Recently, a friend of mine asked when we might be able to see a comet. He was surprised when I said there are several visible right now.

A cat-looking view of Comet 67P from the Rosetta mission.

See a Comet Cat and Other Amazing Rosetta Views in This 70,000-Photo Archive

By Elizabeth Howell

Can you spot a cat in this cosmic image? This photo — just one of 70,000 available in a new Rosetta spacecraft image archive — has a cometary view that looks like a cat's face from side-on.

Scientists found the carbon-rich fragment of a comet embedded within a meteorite (at white arrow). The meteorite's colors can be seen by shining polarized light through a thin slice, and the grid lines show intervals of one millimeter.

Rare Comet Fragment Found Inside Rocky Meteorite

By Elizabeth Howell

Researchers have found a piece of a comet — an object made up of ice and dust — inside of a space rock known as a stony meteorite.

The Hubble Space Telescope captured this image of the impact of Shoemaker-Levy 9 fragment G with Jupiter on July 18, 1994.

How a Viral Comet Crash Into Jupiter Helped Popularize the Internet

By Meghan Bartels

A quarter century ago and thousands of miles away, a dramatic weeklong cosmic collision unfolded and helped the internet gain a foothold in people's lives.

Comet 21P/Giacobini-Zinner passes by the open star cluster M37 on Sept. 10, 2018, in this deep-space image by astrophotographer Miguel Claro.

Comet 21P Crosses Paths with a Star Cluster in Sparkling Deep-Space Image

By Miguel Claro

In this deep-space photo, the bright-green Comet 21P/Giacobini-Zinner blazes across a sparkling star field, passing by the open star cluster M37 as it makes its way through the Auriga constellation.

Amazing Photos of Comet 2018/Y1 Iwamoto!

By Hanneke Weitering

Comet C/2018 Y1 Iwamoto

How to See Comet Iwamoto Fly Past Earth This Week

By Hanneke Weitering

The brilliant, blue-green comet C/2018 Y1 Iwamoto will zip by Earth this week, and the speedy space "snowball" is currently visible in the night sky with binoculars and small telescopes.

'Oumuamua

Interstellar Object 'Oumuamua Could Be a 'Monstrous' Corpse of Comet Dust

By Meghan Bartels

'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.

Titan, Saturn and rings

Saturn's Biggest Moon Titan May Bake Its Own Atmosphere

By Sarah Lewin

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

Interstellar Asteroid ’Oumuamua

1st Interstellar Visitor 'Oumuamua Is Actually Not That Special

By Hanneke Weitering

The surface features of Kuiper Belt object Ultima Thule (2014 MU69) are coming into focus in these images taken by NASA's New Horizons spacecraft during its historic flyby on Jan. 1, 2019. These images, released Jan. 2, were taken a day earlier from a dis

'Ultima Thule': Nickname for New Horizons' Target Celebrates Exploration, Not Nazis, Scientist Says

By Meghan Bartels

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

Comet 46P/Wirtanen

Christmas Comet 46P Is Making the Season Bright (and Green) for Scientists

By Elizabeth Howell

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.

Comet 46P/Wirtanen from Madrid

That Eerie Green Comet Visible in the Night Sky Now? We Almost Sent a Probe There.

By Meghan Bartels

Comet 46P/Wirtanen

How to See Ghostly Green Comet 46P/Wirtanen Fly by Earth This Weekend

By Elizabeth Howell

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.

Comet 46P/Wirtanen

Geminid Meteor Shower and Shining Comet 46P/Wirtanen Star in Slooh Webcast: How to Watch

By Sarah Lewin

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.

Comet 46P/Wirtanen

Amazing Photos: Brilliant Comet 46P/Wirtanen Wows Stargazers

By Christine Lunsford

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