| Dictionary, Encyclopedia and Thesaurus - The Free Dictionary 3,900,018,093 visitors served. |
Dictionary/ thesaurus | Medical dictionary | Legal dictionary | Financial dictionary | Acronyms | Idioms | Encyclopedia | Wikipedia encyclopedia | ? |
Evection |
Also found in: Dictionary/thesaurus, Wikipedia | 0.01 sec. |
|
|
evection [ē′vek·shən]
(astrophysics) A perturbation of the moon in its orbit due to the attraction of the sun. Evection the greatest disparity—that is, deviation from motion according to Kepler’s laws—in the moon’s motion around the earth, caused by perturbation by the sun. Discovered by Hip-parchus in the second century B.C., evection was detected by Ptolemy in the second century A.D. and was correctly explained by I. Newton. The change in the moon’s longitude owing to evection reaches 1°16’26” and varies with a period of approximately 31.8 mean solar days. The perturbing force that causes evection also changes the horizontal parallax of the moon periodically. Want to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit the webmaster's page for free fun content. |
|
| Encyclopedia |
| Free Tools: |
For surfers:
Free toolbar & extensions |
Word of the Day |
Help
For webmasters: Free content | Linking | Lookup box | Double-click lookup |
|---|