Inclination
Inclination is the angle by which an orbit is tilted compared with Earth's orbital plane.
Inclination is the angle between an object's orbit and a reference plane, usually the ecliptic, the plane of Earth's orbit around the Sun. An inclination of 0 degrees means the orbit lies flat in the same plane. Values up to 90 degrees mean the orbit is tilted, and values above 90 degrees mean the object travels in the opposite direction to the planets, called retrograde.
The planets have low inclinations, all within about 7 degrees of the ecliptic. Most asteroids are within about 20 to 30 degrees. Comets can have any inclination: Halley's Comet has an inclination of about 162 degrees, so it orbits backwards.
Inclination affects meteors. Particles on retrograde orbits, such as those from Halley's Comet, meet Earth almost head-on, producing fast meteors around 66 kilometres per second in the Orionids and Eta Aquariids. Particles moving in the same direction as Earth catch us more slowly, giving slower meteors.
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