The distance of an object from the sun, usually given in astronomical units. This represents the estimated brightness of the comet when compared to stars around it. The memorized comet's appearance is then compared to the defocused stars to determine the comet's brightness. In meteor astronomy the magnitude of a meteor is compared to that of other stars in the sky. The magnitude scale is set up so that the brighter magnitudes are actually represented by smaller numbers.
Most meteors originate from comets.
A meteor that is large enough to survive its passage through the atmosphere and hit the ground. A shower of meteors occurs when Earth's orbit intersects the orbit of a meteor stream. This is a rare event that occurs when Earth encounters closely grouped meteors within a meteor stream. Such events can see meteor rates exceeding 1000 per minute. This represents the orbit of meteoroids as they travel around the sun.