Elongation
Contents
Elongation
(glossary entry)Table of Contents
[#Elongation Elongation]
[#Elongation-Description Description]
[#Elongation-Additional Information Additional Information]
[#Elongation-LPOD Articles LPOD Articles]
[#Elongation-Bibliography Bibliography]
Description
The elongation of the Moon is the apparent angular distance of the center of the Moon from the center of the Sun as seen by a particular observer. - JimMosher JimMosher
Additional Information
- The elongation angle is listed as the "Sun-Observer-Target" or "SOT" angle in the lunar output from JPL Horizons.
- It is an approximate determinant of the theoretical percent illumination of the Moon, which is calculated as if the Moon were a perfect sphere (see: phase). - JimMosher JimMosher
- The exact value of the elongation is dependent on the location of the observer. - JimMosher JimMosher
- If the observer is on Earth, the elongation angle is computed neglecting the effects of atmospheric refraction (since that is the angle which determines the lighting pattern, even though the observed separation may be distorted by differences in refraction). - JimMosher JimMosher
- The Moon's elongation approaches zero near the time of New Moon and approaches 180° near the time of Full Moon, but it rarely reaches either of these limits. - JimMosher JimMosher
- It is thought by some that the Moon is intrinsically invisible when the elongation is less than some critical value (see: Danjon limit). - JimMosher JimMosher
- See also: Saber's Beads, which is a curious optical phenomenon related to the very young (and extremely thin) moon's crescent (only a couple of hours after New Moon). Saber's Beads are also observable at the very OLD moon's crescent, a couple of hours before New Moon. - DannyCaes DannyCaes Feb 12, 2008
LPOD Articles
Bibliography
This page has been edited 1 times. The last modification was made by - tychocrater tychocrater on Jun 13, 2009 3:24 pm - mgx2
