Thousands of objects cross the Earth’s orbits all the time. Two such cosmic bodies are Asteroids and Comets. Astronomers believe that the collision of these objects with Earth marks the evolution of our planet.
These objects have similar properties. But some differences need to be kept in mind in the exploration of these cosmic bodies.
- Asteroids are rocky, metallic bodies orbiting the Sun; comets are icy, dusty bodies with distinctive tails.
- Asteroids primarily reside in the Asteroid Belt; comets mostly originate in the Kuiper Belt or Oort Cloud.
- Comets display a tail when nearing the Sun due to sublimation; asteroids do not develop tails.
Asteroid vs Comet
An asteroid is a celestial body composed of rocky materials and metals. It is formed close to the sun. A comet is also a celestial that orbits around the Sun, but it is made up of dust, ice, and rock materials, so when it gets closer to the Sun, its ice and dust content start to vaporize, and it loses its shape.
Asteroids are irregular, spiked-shaped objects that orbit the sun. They are found in the asteroid belt which is located between the two planets, Mars and Jupiter. About size, they are much smaller than planets. Asteroids follow the same path as planets orbiting around the sun.
On the other hand, Comet, in Greek, refers to ‘long haired’. Comets are frosty snowballs composed of dust, rock, and ice. They orbit the sun. As a Comet moves closer to the sun, it gets heated and releases gases and dust. These materials form a dust-like tale in the atmosphere.
|Parameters of Comparison
|Asteroids are made of metals(mostly iron and nickel), rock, and other elements.
|Comets are made of frozen gas(mainly methane, ammonia, and carbon dioxide), dust, ice, and rock.
|They are found at a closer distance to the sun.
|They are found at a safe distance from the sun.
|They have a narrower orbit. Most of them are found in the asteroid belt located between Mars and Jupiter.
|They have a much more elongated orbit lying beside the orbit of Pluto.
|It does not produce any dust tail.
|It produces a dust tail when moved closer to the sun.
|Orbiting the Sun
|All the asteroids orbit the sun.
|Most of the comets follow the orbit of the sun but some of them lie outside our solar system.
What is Asteroid?
Asteroids are rocky objects that were formed from the remains left after the formation of our solar system. Millions of asteroids are present in the asteroid belt.
They are so far apart that you cannot see another asteroid while standing on one asteroid. Asteroids are thousands of miles apart from each other.
The term asteroids mean ‘star-like as they appear like a star when seen through a microscope. Asteroids are smaller in size than planets, and they are sometimes called ‘minor planets’ or planetoids. Just like planets, they orbit the Sun. Small asteroids are called meteoroids.
Asteroids range from a few miles to several thousand miles in diameter. The composition of asteroids is based on their distance from the Sun. As of 2020, 1,000,000 asteroids have been discovered.
The largest asteroid is Ceres which is about a quarter of the size of the moon. It was discovered in 1801 by astronomer Giuseppe Piazzi. It was the first discovered asteroid. It was first disguised as a planet but later labeled as Asteroid due to its properties.
Despite the presence of huge numbers of asteroids in the solar system, their mass is considered to be less than the mass of the moon.
What is Comet?
Comets are dusty frozen balls orbiting the sun. They are called ‘dusty snowballs.’ They are located at a distance far beyond the Sun. As they get closer to the sun, they come in contact with heat. As a result, their outer layer, made of ice, melts down and spews in space.
Their closeness to the Sun makes them appear bright and visible to the naked eye. Upon melting, their tails extend to a million kilometers into space and thus making them appear huge. It is said that comets travel in our solar system in a series of straight lines.
Gottfried Kirch was the first person to mark the telescopic discovery of a Comet in 1680. The most famous Comet is the comet Hally. It has a large nucleus and appears extremely bright.
It is the only comet that is visible from Earth. It appears every 75 or 76 years and is visible to the naked eye. When two comets collapse into each other, they change their direction and move closer to the sun.
Main Difference Between Asteroid And Comet
- Asteroids are formed in the asteroid belt between Mars and Jupiter, and some are present in other places, whereas Comets are formed in the outermost region of the solar system.
- Asteroids are made up of rock and metals. On the other hand, Comets are like dusty snowballs which are formed in space. They are made up of dirt, ice, water, and gases.
- Asteroids have an elliptical orbit, whereas Comets have an eccentric orbit.
- Asteroids have shorter orbital periods consisting of one to a hundred years, whereas Comets have much longer orbital periods consisting of seventy-five to a million years.
- Asteroids do not produce tail-like structures. On the other hand, when Comets come closer to the sun, the outer structure that was made up of ice melts down and releases gases which make them appear like a dust tail falling from the sky.
Last Updated : 19 July, 2023
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.