Specifically, inclination is one of the six orbital elements that describe the shape and direction of celestial bodies' orbits. It is the orbital plane and reference plane of the planet (usually Ecliptic or equator The angular distance between) and is described in terms of angle. In the solar system, the inclination of a planet's orbit is defined as the angular distance between the planet's orbital plane and the ecliptic, the plane where the Earth orbits the sun. It may also be measured in another plane, such as the equator of the sun or the orbital plane of Jupiter, but for observers on Earth, the ecliptic plane is the most practical.
Most of the orbital planes of planets in the solar system have a small inclination to each other and to the solar equator. The notable exceptions are Pluto and Eris, the dwarf planets, whose inclinations are 17 degrees and 44 degrees respectively; There are also asteroids in the Zhishen Star inclination of 34 degrees. Many known exoplanets Planetary system Some of them are high dip. Satellite or Artificial satellite If the inclination angle is close enough to the planets, it will be measured by the equatorial plane of the planets they surround. The equatorial plane is the plane perpendicular to the axis of rotation and passing through the center. (1) The inclination of 0 degrees means that the orbit around the object is on the equatorial plane of the planet and is consistent with the direction of the planet's movement; For example: geostationary orbit satellite (GEO satellite)
(2) The 90 degree inclination angle is the orbit around the pole. The spacecraft will pass the planet's south and north poles. In addition;
(3) An inclination of 180 degrees is a retrograde orbit in the equatorial plane.
If the object is far away from the central object, another reference plane is needed: the Laplacian plane. When away from the main star, the Laplacian plane is separated from the equatorial plane, and the angle of deviation is increasing until there is the maximum angular distance from the orbital plane of the main star.
For a celestial body whose axis of rotation is unknown or unclear, a satellite will take the ecliptic plane as the reference for measurement. Sometimes (for a slowly moving celestial body) it will be relative to the plane of the sky (see the definition of conjoined star below).
For the moon, its inclination is relative to the earth equator Plane, which leads to rapid changes in its values and large variables, so it will be more reasonable to measure it relative to the ecliptic (which means that the moon and the earth revolve around the sun together), and it is almost a constant value. Rail inclination | name | Ecliptic dip | The inclination of the equator of the sun | Constant plane inclination |
|---|
terrestrial planet | Mercury | 7.01° | 3.38° | 6.34° |
Venus | 3.39° | 3.86° | 2.19° |
earth | zero | 7.155° | 1.57° |
Mars | 1.85° | 5.65° | 1.67° |
Gaseous planet | Jupiter | 1.31° | 6.09° | 0.32° |
Saturn | 2.49° | 5.51° | 0.93° |
Uranus | 0.77° | 6.48° | 1.02° |
Neptune | 1.77° | 6.43° | 0.72° |
For planets and other celestial bodies in operation, the inclination of the rotation axis is the angle between the normal line and the orbital plane, but it is more clear to use the axial tilt or inclination of the rotation axis.
Specifically, for Earth, the inclination of the ecliptic is the angle between the ecliptic plane and the equatorial plane.
The inclination of objects outside the solar system, such as conjoined stars, is defined as the angle between the normal line of the orbital plane (that is, the axis of the orbit) and the observer's direction because there is no other reference.
Similarly, this can also be regarded as the angle between the orbital plane and the sky plane, because the latter is also defined according to the viewing direction of the observer, so you should be careful when comparing stars in different regions of the celestial sphere. When the inclination of the conjoined stars is close to 90 degrees (sideways), they often eclipse each other.
stay Space dynamics ， Rail inclination It can be calculated by the following formula: Here:
yes Component in Z-direction Is perpendicular to Track plane Track of angular momentum Vector. 
