Can An Asteroid Be Bigger Than A Planet?

The likelihood of an asteroid surpassing a planet in size is very low.

Asteroids and planets are part of the Solar System, the two may look similar, but many differences set them apart in many ways. Planets are generally bigger than asteroids while most asteroids are fragments of former planets that broke away due to some collision. What this means is that the chances of an asteroid being bigger than a planet are very low but possible. There are conditions that objects in the solar system have to meet for them to be classified as planets.

Conditions That Qualify an Object as a Planet

For an object to be classified as a planet in our solar system, it must orbit around the sun. It must also possess sufficient gravity to counter other forces for it to be able to acquire a near equilibrium shape and lastly it must have the force to clear its neighborhood of other objects. Asteroids, on the other hand, clear only two of these three conditions except the last one and as much as they have a gravitational force it is not as impressive as those of the planets no matter the size. So can an asteroid be bigger than a planet? The answer is, not likely.

Asteroid Sizes and Planets

The smallest planet in the solar system is Mercury which has a diameter of about 3,032 miles. This way bigger than the most massive asteroid ever recorded, Ceres, which is about 587 miles long in diameter. This, however, is not the limit for both planets and asteroids as far as sizes are concerned. The possibility of having an asteroid bigger than Ceres is high but until such an object is discovered, the consensus remains that the likelihood of an asteroid surpassing a planet in size is very low.

Similarities Between Asteroids And Planets

Both are objects that are bound by the sun's immense gravitational force which is responsible for the orbital revolution. Both asteroids and planets are made of almost similar minerals with iron being the most prevalent. Both have uneven surfaces that are a result of different forces like collisions with other objects.


When it comes to numbers, asteroids have the upper hand as they are scattered across the solar system clustered in belts between planets. It is estimated that the asteroid belt contains more than 1.9 million asteroids with diameters that are 1 mile long and above. This proximity to each other had led to many cases of asteroids crossing paths with planets and leading to impacts.

Famous Asteroids

Some of the best-known asteroids are Ceres which is the biggest with a diameter of about 587 miles. Similarly, Pluto was downgraded from being a planet to a distinct dwarf planet and has a diameter of 1,474 miles. There is the Pallas asteroid which is 300 miles in diameter, and lastly, there is Vesta which is roughly 250 miles in diameter. These three are the best-known asteroids due to their extraordinary sizes. Ceres was recently reclassified as a dwarf planet due to its proximity to the sun and the presence of gravitational forces.


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