Difference Between Asteroid and Comet

Celestials bodies like asteroids and comets are “time capsules” that contain information about the history of our solar system, making them interesting targets of studies. The main difference between asteroid and comet is their composition. Asteroids and comets are debris left over from the formation of moon and planets. Comets are located in the outermost regions of the solar system, while, asteroids are located in a belt between Jupiter and Mars.

Occasionally, comets and asteroids change their orbital path due to gravitational disturbances, sometimes bringing them close to a planet. Craters on the moon and planets are an evidence of the history of impacts with comets and asteroids.

Comets are made of dust, ice and rock materials, while asteroids are composed of rocky materials and metals. Both the celestial bodies were formed 4.6 billion years ago. Asteroids were formed much closer to the sun where it was impossible for the ice to remain solid. Comets were formed farther away from the sun where the ice remained solid. Comets which approach the sun lose material with its each orbit around the sun as its ice melts and vapourises to form the tail known as coma.


Asteroid orbit the Sun and are small bodies on the solar system. They are made up of metals and rocks and also consists of organic compounds. They are similar to comets but don’t have a coma-like comet. Asteroids tend to have shorter and elliptical orbits. Astronomers have discovered millions of asteroids some that measure hundreds of kilometers across and some as small as dust particles.


Comets also orbit the Sun and are relatively small bodies of the solar system. When comets approach the sun, some part of their ice melts. When some part of the ice melts, the other materials vapourise due to the heat of the sun. This results in a glowing halo that extends outwards as though sailing through space. The ice and compounds like ammonia and methane develop a fuzzy cloud like shell known as the coma. This forms a notable difference between comets and asteroids.  

Difference Between Asteroid And Comet

Difference Between Asteroid And Comet
Asteroid Comet
Asteroids have elliptical orbit Comets have an eccentric orbit.
It is made of metals and rocks Made of rocks, hydrocarbons, and ice
Do not produce a coma or tail atmosphere Thin, temporary atmospheric tail when close to the Sun.
The orbital period is 1 to 100 years The orbital periods is 75 to more than 100,000 years.
1 to larger than 100 kilometers in size 1 to 10 kilometer in size (nucleus only)

The above mentioned were a few differences between comet and asteroid. How likely is it that our planet could get hit by a comet or a large asteroid? We are aware that earth has been hit many times in the past by comets and asteroids whose orbit bring them close to the earth. There has been evidence proving that cosmic collisions played a major role in mass extinctions. Though, none at this time pose threat to earth!