How Big Is The Asteroid Belt?

The planets in our solar system are divided into two separate regions: the rocky worlds of the inner solar system and the gas giants of the outer solar system. Interestingly, there is a structure that separates the two regions of the solar system, located between the outermost rocky planet, Mars, and the innermost gas giant, Jupiter. That structure is the Asteroid Belt

Size Of The Asteroid Belt

Asteroid Belt
Artistic rendition of the Asteroid Belt

The Asteroid Belt has an estimated size of 140-million miles (225-million kilometres) across. That’s about 1.5 times larger than the distance between the Earth and sun. The Asteroid Belt is located anywhere from 300 to 390-million miles (480 to 628-million kilometres) away from the Earth. The closest planet to the Asteroid Belt is Mars, which is located about 47-million miles (75-million kilometres) from the innermost region of the Asteroid Belt. Beyond the Asteroid Belt is Jupiter, which is located much further away from the Asteroid Belt than Mars is. On average, Jupiter is located 242-million miles (375-million kilometres) away from the Asteroid Belt. 

Mass Of The Asteroid Belt

Ceres is the most massive object in the Asteroid Belt. Image credit: NASA

Despite the immense size of the Asteroid Belt, its mass is actually very small. Although the Asteroid Belt contains millions of asteroids, all of it adds up to only about 3% the mass of Earth’s moon. If you were to combine every asteroid into a single object, it would be significantly smaller than the moon. In fact, over 60% of the total mass in the Asteroid Belt is contained within just four objects, Ceres, Vesta, Pallas, and Hygiea. Nearly 40% of the mass is contained within Ceres alone, making it the largest object in the Asteroid Belt and the only dwarf planet located in the inner solar system. 

Traversing The Asteroid Belt

Asteroid Vesta
Image of the asteroid Vesta. Image credit: NASA

While sci-fi movies and films have popularized the idea that travelling through an asteroid belt is exceedingly dangerous, this is not actually the case. In fact, every spacecraft that has travelled beyond Mars has entered the Asteroid Belt with no issue. While works of sci-fi make it appear as though collisions with asteroids are a real danger, the actual distances between individual asteroids is so vast that a collision is exceedingly unlikely. In fact, if you were to stand on an asteroid within the Asteroid Belt, you would not be able to identify even the closest asteroids. Their distance would make them look no different from the distant stars.