Editing Earth's orbit (section)

==Influence on Earth==
{{Main|Season}}

Because of Earth's [[axial tilt]] (often known as the obliquity of the [[ecliptic]]), the inclination of the Sun's trajectory in the sky (as seen by an observer on Earth's surface) varies over the course of the year. For an observer at a northern latitude, when the north pole is tilted toward the Sun the day lasts longer and the Sun appears higher in the sky. This results in warmer average temperatures, as additional solar radiation reaches the surface. When the north pole is tilted away from the Sun, the reverse is true and the weather is generally cooler. North of the [[Arctic Circle]] and south of the [[Antarctic Circle]], an extreme case is reached in which there is no daylight at all for part of the year, and continuous daylight during the opposite time of year. This is called [[polar night]] and [[midnight sun]], respectively. This variation in the weather (because of the direction of the Earth's axial tilt) results in the [[season]]s.<ref>{{Cite web|url = http://spaceplace.nasa.gov/seasons/en/|title = What causes the seasons? (NASA)|access-date = January 22, 2015}}</ref>