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:
“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)
“I repeat, sir, that in whatever position you place a woman she is an ornament to society and a treasure to the world. As a sweetheart, she has few equals and no superiors; as a cousin, she is convenient; as a wealthy grandmother with an incurable distemper, she is precious; as a wet-nurse, she has no equal among men. What, sir, would the people of the earth be without woman? They would be scarce, sir, almighty scarce.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)
“My position is a naturalistic one; I see philosophy not as an a priori propaedeutic or groundwork for science, but as continuous with science. I see philosophy and science as in the same boat—a boat which, to revert to Neurath’s figure as I so often do, we can rebuild only at sea while staying afloat in it. There is no external vantage point, no first philosophy.”
—Willard Van Orman Quine (b. 1908)