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Eclipse Magnitude and Obscuration

 
Use the third scollbar ("Moon Center") to move the Moon.

The eclipse magnitude is defined as the fraction of the Sun's diameter occulted by the Moon, and the eclipse obscuration as the fraction of the Sun's surface area occulted by the Moon.

The area covered by the the moon can easily be computed:

 

 The area of the segment is:

The secant P1P2 is at:

and the angles are:


Diameters: dMoon/dSun= 1


Diameters: dMoon/dSun= 1.1 (total eclipse)


Diameters: dMoon/dSun= 0.9 (annular eclipse)


Diameters: dMoon/dSun= 0.9, 1.0, and 1,1


Select Data from the menu to get this window:

Magnitudes of Solar Eclipses 2006 - 2010 (Fred Espeneak):

2006 Mar 29
1.052
Total
2006 Sep 22
0.935
Annular
2007 Mar 19
0.874
Partial
2007 Sep 11
0.749
Partial
2008 Feb 07
0.965
Annular
2008 Aug 01
1.039
Total
2009 Jan 26
0.928
Annular
2009 Jul 22
1.080
Total
2010 Jan 15
0.919
Annular
2010 Jul 11
1.058
Total

Web Links

Calculating the area of the Sun covered during an eclipse

Javascript Eclipse Calculator V3.2b2

Solar Eclipse Page (Fred Espenak)

(c) 2006-2023 J. Giesen

Modified: 2023,  Oct 07