This is one of the most commonly misused terms. A Meteoroid is one of the countless small solid bodies in space, some no larger than a grain of sand. When it enters the Earth’s atmosphere and ignites due to air friction, we see it as a streak of light that is then known as a Meteor. If it does not disintegrate entirely and lands on the Earth, only then is it referred to as a Meteorite. Sizes range from submicroscopic particles to bodies approaching the size of a small asteroid (also known as a planetesimal). Composition ranges from silicates to nickel-iron metal.