Online Encyclopedia

Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.

INVARIABLE PLANE

Online Encyclopedia
Originally appearing in Volume V14, Page 717 of the 1911 Encyclopedia Britannica.
» Make a correction to this article.
» Add information or comments to this article.
Spread the word: del.icio.us del.icio.us it!

INVARIABLE See also:

PLANE , in See also:celestial See also:mechanics (see See also:ASTRONOMY), that plane on which the sum of the moments of momentum of all the bodies which make up a See also:system is a maximum. It derives its celebrity from the demonstration by See also:Laplace that to whatever mutual actions all the bodies of a system may be subjected, the position of this plane remains invariable. A conception of it may be reached in the following way. Suppose that from the centre of gravity of the See also:solar system (instead of which we may, if we choose, take the centre of the See also:sun), lines or radii vectores be See also:drawn to every See also:body of the solar system. As the See also:planet revolves around the centre, each See also:radius vector describes a See also:surface of which the See also:area swept over in a unit of See also:time See also:measures the areal velocity of the planet. The constancy of this velocity in the See also:case of the sun and a single planet is formulated in See also:Kepler's second See also:law. Next pass any plane through the centre of See also:motion and project the area just defined upon that plane. We shall thus have a projected areal velocity, the product of which by the See also:mass of the planet is the moment of momentum of the latter. See also:Form this product for every body or mass of See also:matter in the system, and the sum of the moments is then invariable whatever be the direction of the plane of See also:projection. In the case of a single body revolving around the sun this plane is that of its See also:orbit. When all the bodies of the system are taken into See also:account, the invariable plane is a certain mean among the planes of all the orbits. In the case of the solar system the moment of See also:Jupiter is so preponderant that the position of the invariable plane does not deviate much from that of the orbit of Jupiter.

The See also:

influence of Saturh comes next in determining it, that of all the other See also:planets is much smaller. The latest computation of the position of this plane is by T. J. J. See, whose result for the position of the invariable plane is inclination to See also:ecliptic 10 35' 7°'74, See also:longitude of See also:node on ecliptic Io6° 8' 46,,.7 (Eq. 1850).

End of Article: INVARIABLE PLANE

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML.
Site content, images, and layout Copyright © 2006 - Net Industries, worldwide.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.

Links to articles and home page are always encouraged.

[back]
INVAR 		[next]
INVENTORY (post-class. Lat. inventarium, a list or ...

Site © 2006 - Net Industries