An asteroid belt is a ring of rocks. The rocks are called asteroids. There is an asteroid belt situated between Jupiter and Mars. It looks a like a torus and has over 200 asteroids that are larger than 100km in diameter. There are between 1 and 2 million asteroids larger than 1 km in diameter and there are many millions of smaller ones too. The biggest object in the belt is called Ceres, Ceres is the asteroid belts only dwarf planet. Ceres is about 950km in diameter, less than half the size of Pluto. The average distance between asteroids is 600 000 miles (966 000km). Asteroids are grouped into 3 types. The C-Type (chondrite) asteroids are made of clay and silicate rocks. They make up 75% of the known asteroids, and are generally darker in colour. The M-Type (metallic) asteroids consist of iron and nickel. These are bright asteroids and make up 17% of the known asteroids. The S-Type (stony) are silicate materials and nickel-iron. They make up 8% of known asteroids.
Not all rocks in our solar system are asteroids though, meteoroids are smaller rocks found throughout our solar system. Meteoroids can be part of asteroids that have broken off. They can be as small as a grain of sand and normally burn up in the atmosphere. When a meteoroid enters the atmosphere it becomes a meteor. If that meteor hits earth it becomes a meteorite.
Near the end of 2017 astronomers spotted a mysterious rock-like thing flying through our solar system. It was named Oumuamua, the Hawaiian word for ‘scout’. At first astronomers believed that it was an asteroid. The mysterious thing about Oumuamua is that when it went past the sun, it turned, as if slingshoted by the sun’s gravity. Astronomers knew that this would be impossible, since Oumuamua was moving to fast to be under the control of the sun’s gravity (70 000 mph). There are multiple theories for the mysterious movement. The most likely of these is that solar radiation pressure may have moved the object. Although another popular theory is that it was an alien spaceship.