Ceres asteroid.(Photo: NASA.)
Giuseppe Piazzi, an Italian astronomer, discovered the largest Ceres asteroid in the solar system in 1801. This giant asteroid has orbit between Mars and Jupiter. Ceres is so big that its diameter is up to 940km, a quarter of the estimated total mass of all asteroids in the asteroid belt combined. Currently, Ceres is considered a dwarf planet.
The asteroid near the Earth is an asteroid located less than 44 million kilometers from Earth's orbit. As of June 2017, scientists discovered all 16,209 near-Earth asteroids, of which 1,803 asteroids are potentially dangerous.
Every year there is usually an asteroid-sized asteroid that collides with Earth's atmosphere. It will then turn into a giant fireball and be completely burned before reaching the ground.
Based on specific orbital properties, asteroids can assemble into asteroid groups. The moons of asteroids are orbiting asteroids larger than asteroids.
Scientists estimate that about 1/6 of asteroids have a small companion moon. Even some asteroids still have two moons.
In 1993, scientists discovered the first asteroid-moon system, the Ida and the Moon Dactyl.