A micrometeorite is an extraterrestrial particle, ranging in size from 50 µm to 2 mm, collected on the Earth's surface. Micrometeorites are micrometeoroids which have survived entry through the Earth's atmosphere. They differ from meteorites in being smaller, more plentiful and different in composition and are a subset of cosmic dust, which also includes the smaller interplanetary dust particles (IDPs). Micrometeorites enter the Earth's atmosphere with high velocities (at least 11 km/s) and undergo heating through atmospheric friction and compression. Individual micrometeorites weigh between 10^-9 and 10^-4 g and collectively contribute most of the extraterrestrial material that has come to the present day Earth. Fred Lawrence Whipple first coined the term "micro-meteorite" to describe dust-sized objects that fall to the Earth. Sometimes meteoroids and micrometeoroids entering the Earth's atmosphere are visible as meteors or "shooting stars", whether or not they reach the ground and survive as meteorites and micrometorites.