Asteroid
Although their location in the asteroid belt excludes them from planet status, the three largest objects, Ceres, Vesta, and Pallas, are intact protoplanets that share many characteristics common to planets, and are atypical compared to the majority of "potato"-shaped asteroids. The fourth largest asteroid, Hygiea, has an undifferentiated interior, like the majority of asteroids. Between them, the four largest asteroids constitute half the mass of the asteroid belt.
Impact event
Stony asteroids with a diameter of enter Earth's atmosphere approximately once per year. Asteroids with a diameter of 7 meters enter the atmosphere about every 5 years with as much kinetic energy as the atomic bomb dropped on Hiroshima (approximately 16 kilotons of TNT), but the air burst is reduced to just 5 kilotons. These ordinarily explode in the upper atmosphere and most or all of the solids are vaporized. However, asteroids with a diameter of , and which strike Earth approximately twice every century, produce more powerful airbursts. The 2013 Chelyabinsk meteor was estimated to be about 20 m in diameter with an airburst of around 500 kilotons, an explosion 30 times the one over Hiroshima. Much larger objects may impact the solid earth and create a crater.