Astronomy Picture of the Day
    


Equinox Earth
<< Yesterday 28.09.2013 Tomorrow >>
Equinox Earth
Credit & Copyright: Roscosmos / NTSOMZ / zelenyikot.livejournal.com - Courtesy: Igor Tirsky
Explanation: From a geostationary orbit 36,000 kilometers above the equator, Russian meteorological satellite Elektro-L takes high-resolution images our fair planet every 30 minutes. But only twice a year, during an Equinox, can it capture an image like this one, showing an entire hemisphere bathed in sunlight. At an Equinox, the Earth's axis of rotation is not tilted toward or away from the Sun, so the solar illumination can extend to both the planet's poles. Of course, this Elektro-L picture was recorded on September 22nd, at the northern hemisphere's autumnal equinox. For a moment on that date, the Sun was behind the geostationary satellite and a telltale glint of reflected sunlight is seen crossing the equator, at the location on the planet with satellite and sun directly overhead (5MB animated gif).

January
February
March
April
May
June
July
August
September
October
November
December
 < September 2013  >
Mo Tu We Th Fr Sa Su






1
2345678
9101112131415
16171819202122
23242526272829
30





Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.

Based on Astronomy Picture Of the Day

Publications with keywords: Earth - equinox
Publications with words: Earth - equinox
See also:
All publications on this topic >>