Position
All planetary orbital planes wobble around the invariable plane, meaning that they rotate around its axis while their inclinations to it vary, both of which are caused by the gravitational perturbation of the other planets. That of Earth rotates with a quasi-period of 100,000 years and an inclination that varies from 0.1° to 3°. If long-term calculations are performed relative to the present ecliptic, which is inclined to the invariable plane by about 1.5°, it appears to rotate with a period of 70,000 years and an inclination that varies between 0° and 4°. Specifically, Earth's orbit (the ecliptic) is inclined to the invariable plane by 1°34'59"−18"T, where T is the number of centuries since 1900. Its J2000.0 value is 1°34'43.3". The inclination of the orbit of Jupiter to the invariable plane varies over the range of 14'–28'.
Read more about this topic: Invariable Plane
Famous quotes containing the word position:
“When asked whether or not we are Marxists, our position is the same as that of a physicist or a biologist who is asked if he is a “Newtonian” or if he is a “Pasteurian.””
—Ernesto “Che” Guevara (1928–67)
“The essence of spirit, he thought to himself, was to choose the thing which did not better one’s position but made it more perilous. That was why the world he knew was poor, for it insisted morality and caution were identical.”
—Norman Mailer (b. 1923)
“Beauty ought to look a little surprised: it is the emotion that best suits her face.... The beauty who does not look surprised, who accepts her position as her due—she reminds us too much of a prima donna.”
—E.M. (Edward Morgan)