Animated GIF of comet approaching and receding.


Comets are frozen leftovers from the formation of the solar system composed of dust, rock, and ices. They range from a few miles to tens of miles wide, but as they orbit closer to the Sun, they heat up and spew gases and dust into a glowing head that can be larger than a planet. This material forms a tail that stretches millions of miles.

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Comets are cosmic snowballs of frozen gases, rock, and dust that orbit the Sun. When frozen, they are the size of a small town. When a comet's orbit brings it close to the Sun, it heats up and spews dust and gases into a giant glowing head larger than most planets. The dust and gases form a tail that stretches away from the Sun for millions of miles. There are likely billions of comets orbiting our Sun in the Kuiper Belt and even more distant Oort Cloud.

As of July 22, 2024, the known number of comets, including fragments, is 3,956, according to the NASA/JPL's Solar System Dynamics website.

Featured Comets

Closeup view of a peanut-shaped comet with sunlight reflecting off it

Comet 103P/Hartley (Hartley 2)

Dark sky with streaks of light from the Perseid meteor shower.


An image of comet Borrelly with sunlight reflecting off it.

Comet 19P/Borrelly

Image of Comet Halley


Jet erupting from comet.


bluish comet trailing dust and gas as it travels through space.

Comet 2I/Borisov

Image of comet 2P/Encke


Two close up images of Comet Wild 2

81P/Wild (Wild 2)

Image of potato-shaped comet soon after NASA's Deep Impactor spacecraft hit the comet. Bright light is glowing from one end of the comet.

9P/Tempel 1

Image of comet Hale-Bopp

C/1995 O1 (Hale-Bopp)

Bright comet is seen above red Mars against a backdrop of stars

C/2013 A1 Siding Spring

Comet with bluish tinted tail

C/2012 S1 (ISON)

Artist's concept of cigar-shaped space rock.


Comet Shoemaker-Levy 9

Shoemaker-Levy 9

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