Earth's orbit

Earth's orbit is the approximately elliptical path Earth follows around the Sun, with a mean distance of about 150 million kilometers. Its changing distance and orientation shape aspects of Earth's motion and seasons.

Kepler's laws of planetary motion: Three mathematical laws describing how planets orbit the Sun, including their elliptical paths and changing orbital speeds. They describe the shape and speed variation of Earth's orbit.
Astronomical unit: A unit of length defined as exactly 149,597,870,700 meters, approximately Earth's mean distance from the Sun. It provides the standard scale for Earth's orbital size.
Seasons: Recurring annual periods marked by characteristic daylight and temperature patterns. Earth's axial tilt during its orbit causes the seasons, not its changing distance from the Sun.
Moon's orbit: The Moon's approximately elliptical path around Earth, perturbed by the Sun's gravity. It is a satellite orbit nested within Earth's orbit around the Sun.
Orbital eccentricity: A measure of how much an orbit deviates from a circle. It quantifies how elliptical Earth's path is.
Sidereal year: The time Earth takes to complete one orbit relative to distant stars, about 365.256 days. It measures one revolution of Earth around the Sun against the stars.
Equation of time: The difference between apparent solar time and mean solar time over the year. Earth's orbital eccentricity and axial tilt make apparent solar time vary.
Solar orbit: The path the Sun and solar system follow around the center of the Milky Way. Earth's yearly orbit is part of the solar system's much larger galactic motion.
Perihelion: The point in an orbit at which an object is closest to the Sun. Earth reaches this point in early January.
Ecliptic: The plane of Earth's orbit around the Sun, extended as a great circle across the sky. Earth's orbital plane defines the ecliptic.

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