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Ignoring the influence of other Solar System bodies, Earth's orbit, also called Earth's revolution, is an ellipse with the Earth–Sun barycenter as one focus with a current eccentricity of 0.0167. Since this value is close to zero, the center of the orbit is relatively close to the center of the Sun (relative to the size of the orbit).
Earth's rotation axis moves with respect to the fixed stars (inertial space); the components of this motion are precession and nutation. It also moves with respect to Earth's crust; this is called polar motion. Precession is a rotation of Earth's rotation axis, caused primarily by external torques from the gravity of the Sun, Moon and other bodies.
Heliographic coordinate systems are used to identify locations on the Sun's surface. The two most commonly used systems are the Stonyhurst and Carrington systems. They both define latitude as the angular distance from the solar equator, but differ in how they define longitude. In Stonyhurst coordinates, the longitude is fixed for an observer on ...
Solar rotation varies with latitude. The Sun is not a solid body, but is composed of a gaseous plasma. Different latitudes rotate at different periods. The source of this differential rotation is an area of current research in solar astronomy. [1] The rate of surface rotation is observed to be the fastest at the equator (latitude φ = 0°) and ...
The Sun's path affects the length of daytime experienced and amount of daylight received along a certain latitude during a given season. The relative position of the Sun is a major factor in the heat gain of buildings and in the performance of solar energy systems. [1] Accurate location-specific knowledge of sun path and climatic conditions is ...
In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and orbital plane. [1] It differs from orbital inclination. At an obliquity of 0 degrees, the two axes point in ...
The prime meridian is the centre of the near side of the Moon. A planetary coordinate system (also referred to as planetographic, planetodetic, or planetocentric) [ 1][ 2] is a generalization of the geographic, geodetic, and the geocentric coordinate systems for planets other than Earth. Similar coordinate systems are defined for other solid ...
Kepler's first law placing the Sun at the focus of an elliptical orbit Heliocentric coordinate system (r, θ) for ellipse. Also shown are: semi-major axis a, semi-minor axis b and semi-latus rectum p; center of ellipse and its two foci marked by large dots. For θ = 0°, r = r min and for θ = 180°, r = r max.