Difference between Asteroid and Comet


Celestial bodies like asteroids and comets are “time capsules” that contain information about the history of our solar system, making them interesting targets for studies. The main difference between asteroids and comets is their composition. Asteroids and comets are debris left over from the formation of the moon and planets. Comets are located in the outermost regions of the solar system, while most 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 evidence of the history of impacts with comets and asteroids.
Difference Between Asteroid And Comet
Comets are made of dust, ice, and rock materials, while asteroids are composed of rocky materials and metals. Both 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 that approach the Sun lose material with every orbit around it as its ice melts and vaporizes to form the tail known as the coma.


Asteroids orbit the Sun and are small bodies in the solar system. They are made up of metals and rocks and also consist 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 kilometres 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 parts of the ice melt, the other materials vaporize 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 is a notable difference between comets and asteroids.  

Difference Between Asteroid And Comet

Now that we have an idea of what asteroids and comets are, let us write down the differences between them in a table. The comparison between asteroid and comet is given below.

Difference Between Asteroid and Comet
Asteroid Comet
Asteroids have an 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 are 75 to more than 100,000 years.
1 to larger than 100 kilometres in size 1 to 10 kilometres in size (nucleus only)

The above-mentioned points were a few differences between comet and asteroid. We know that the earth has been hit many times by comets and asteroids whose orbit brings 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 a threat to earth! You can learn more differences between various celestial bodies like the difference between meteors and meteorites at BYJU’S.  

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  1. Very useful and helpful! Thank you very much!

  2. I understood perfectly