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

A sunrise with a comet in the sky

Green comet Nishimura survives its superheated slingshot around the sun. Will we get another chance to see it?

By Harry Baker published

Comet Nishimura, which was only discovered in August, has survived its closest approach to the sun and will brighten over the next week. But is it still visible from Earth?

a comet appears as a white streak on a blue background

Comet Nishimura photobombs NASA spacecraft after its close encounter with the sun (photos)

By Robert Lea published

Comet Nishimura has surprised NASA by photobombing its STEREO spacecraft, revealing it seems to have held together after its brush with the sun on Sept. 17.

a green comet with a faint tail in the sky against a backdrop of stars

Are we about to see a rare green comet light up the sky? An expert explains what to expect from Comet Nishimura

By Jonti Horner published

There's a slight chance Comet Nishimura might brighten unexpectedly. Astronomer Jonti Horner explains what to expect.

a comet in the night sky

See Comet Nishimura at its closest point to Earth this week. It won't visit again for 435 years.

By Brett Tingley published

The newfound Comet P1 (Nishimura) passes its closest point to Earth on Tuesday (Sept. 12). Here's how to see it this week before it's gone for 400 years.

a comet in the night sky

Newfound Comet Nishimura got its tail blown off by a solar storm. It grew back and still looks gorgeous (photos)

By Brett Tingley published

Astrophotographers worldwide have been snapping incredible photos of Comet Nishimura as it makes its way through the solar system.

a green comet with a faint tail in the sky against a backdrop of stars

Will newfound Comet Nishimura really be visible to the naked eye? Experts aren't so sure

By Joe Rao published

While social media has been abuzz with talk of new Comet Nishimura being visible to the naked eye in September, experts aren't so sure.

A blurry image of a comet that appears to have two horns

City-size comet headed toward Earth 'grows horns' after massive volcanic eruption

By Harry Baker published

The exploding comet, known as 12P/Pons–Brooks, is currently approaching its closest point to Earth during its 71-year orbit through the solar system.

green comet visible against a backdrop of stars

Watch 1 month in the life of a green comet during its journey past Earth (video)

By Miguel Claro published

Comet C/2022 E3 made a close pass by our planet in January, and a new video captures its incredible journey in 4K resolution.

a flat rock backlit by the distant sun

Where did the interstellar object 'Oumuamua come from? Its speed could tell us

By Keith Cooper published

The velocity of interstellar objects passing through our solar system, like 'Oumuamua, can be correlated to their chemistry and the type of star they came from.

an illustration showing a comet near Ursa Minor, the little dipper

How to see comet E1 ATLAS high in the night sky in July near the Little Dipper

By Brett Tingley published

A comet discovered just months ago will make for an easy-to-spot, if somewhat dim, target for summer skywatchers eager to see a snowball streak through the solar system.

a blue-green comet in the night sky

40 years ago, a comet came out of the blue in a surprise Earth flyby. Here's what we know now.

By Joe Rao published

Forty years ago this month, there came a show stopping celestial sight — literally a bolt out of the blue — as a new comet was discovered close to Earth.

a large rock in space from which is streaming a white cloudy haze

James Webb Space Telescope discovers water around a mysterious comet

By Robert Lea published

The James Webb Space Telescope has imaged a rare main asteroid belt comet, discovering water around the object that could help reveal how Earth became a wet planet teeming with life.

An artist's depiction of the interstellar comet 'Oumuamua, as it warmed up in its approach to the sun and outgassed hydrogen (white mist), which slightly altered its orbit.

Sorry, E.T. fans: Interstellar visitor 'Oumuamua isn't an alien spacecraft. It's just passing gas.

By Tereza Pultarova published

Since its arrival in the solar system in 2017, interstellar object 'Oumuamua has puzzled scientists. Two American astronomers now think they have solved one of the space rock's biggest mysteries.

a bright comet in the sky over a large antenna dish

A comet coming in 2024 could outshine the stars - if we're lucky

By Joe Rao published

A comet recently discovered zooming through our solar system has the potential to be quite bright when it arrives late in 2024, but comets have let us down before.

a pyramid of light in the night sky

See the night sky shine with ghostly zodiacal light this month

By Robert Lea published

For the next few weeks in March, the sky to the west is illuminated by a pyramid of ethereal glow after twilight known as the zodiacal light.

Comet ISON seen making a close approach to the sun in 2013. A newly discovered comet, C/2023 A3, will appear far brighter in the sky if it survives the sun's rays in fall 2024.

Bright new comet discovered zooming toward the sun could outshine the stars next year

By Stephanie Pappas published

The newly discovered comet C/2023 A3 is making a close approach around the sun for the first time in 80,000 years, and might be as bright as a star in fall 2024.

Comet C/2022 E3 (ZTF) imaged by the Japanese Equuleus cubesat that is orbiting the moon.

Green comet seen from space by Artemis 1 moon mission cubesat (video)

By Tereza Pultarova published

A Japanese cubesat launched aboard NASA's Artemis 1 moon mission took a video of Comet C/2022 E3 (ZTF) earlier this month, about two weeks after the ice ball's closest approach to Earth.

An illustration of the night sky on Feb. 19 showing comet C/2022 A2 (Pan-STARRS) near the constellation Cepheus.

Watch a comet make its 1st and final pass by the sun this weekend

By Robert Lea published

The comet C/2022 A2 (Pan-STARRS) will pass close by the sun on Sunday (Feb. 19), making its first and likely final approach to our star.

A greenish comet streaks through the night sky.

Comet C/2022 A2 (Pan-STARRS) passes close by the sun this weekend

By Stefanie Waldek published

The comet C/2022 A2 (Pan-STARRS) will reach perihelion, or the closest point to the sun in its orbit, on Saturday, Feb. 18. The comet will be visible from Earth at dawn and dusk.

A long-exposure photograph of comet C/2022 E3 (ZTF) taken from Jackson, Wisconsin on Feb. 5, 2023.

Green comet C/2022 E3 (ZTF) may be heading out of the solar system for good

By Robert Lea published

Green comet C/2022 E3 (ZTF) has been predicted to have a period of 50,000 years, but there’s a chance it’s racing out of the solar system.