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:
“One reason—perhaps the chief—of the virility of the Roosevelts is [their] very democratic spirit. They have never felt that because they were born in a good position they could put their hands in their pockets and succeed. They have felt, rather, that being born in a good position, there is no excuse for them if they did not do their duty by the community.”
—Franklin D. Roosevelt (1882–1945)
“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)
“The first full-fledged generation of women in the professions did not talk about their overbooked agenda or the toll it took on them and their families. They knew that their position in the office was shaky at best. . . . If they suffered self-doubt or frustration . . . they blamed themselves—either for expecting too much or for doing too little.”
—Deborah J. Swiss (20th century)