In between Mars and Jupiter is a region of space where most of the asteroids in our solar system hang out. This area is known as the asteroid belt. As of now, we know that there are more than 1/2 million asteroids in the belt, most likely more. Asteroids are “rocky remnants left over from the early formation of our solar system.” (NASA) They come in many different sizes and range from being 590 miles in diameter to only .6 miles in diameter. The largest one, Ceres, is considered a dwarf-planet. It was the first asteroid to be discovered in 1801 by astronomer Father Giuseppe Piazzi. Some asteroids even have their own moons! If we combined the mass of all of the asteroids, the total would be less than Earth’s moon.
There are three composition classes of asteroids, C-, S-, and M-types. Each asteroid is put into a class depending on what materials it is made of. C-type asteroids are the most common and likely consist of “clay and silicate rocks.” (NASA) C-types are also among the oldest items in the solar system. S-type asteroids are made of “silicate materials and nickle-iron.” (NASA) The M-types are made of nickle-iron. Which type of composition an asteroid is depends on how far away from the sun it was when it formed.
Asteroids don’t always stay in the belt, either. They can get kicked out of it for a couple of reasons. This occurs because of Jupiter’s gravity or because of its close encounters with Mars or another object. These changes throw asteroids out of the belt and send them hurtling into space, sometimes towards other planets. Earth has had asteroids and asteroid fragments hit the surface before. Our scientists have methods of tracking asteroids coming toward our planet, such as radar, to help determine the threat level. They can also gather information that helps them learn more about asteroids such as their “orbit, rotation, size, shape, and metal concentration.” (NASA)
Asteroids do not have atmospheres, making it uninhabitable for life as we know it.
I got this information from NASA’s Solar System Exploration site.