A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the Earth's atmosphere and impact with the Earth's surface. When the object enters the atmosphere, various factors like friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate that energy. It then becomes a meteor and forms a fireball, also known as a shooting/falling star; astronomers call the brightest examples "bolides." Meteorites that survive atmospheric entry and impact vary greatly in size. For geologists, a bolide is a meteorite large enough to create a crater.