Is the night sky darkest in the direction opposite the Sun?
No. In fact, a rarely discernable faint glow known as
the gegenschein (German for "counter glow") can be seen 180
degrees around from the Sun in an extremely dark
The gegenschein is sunlight back-scattered off small interplanetary
These dust particles are millimeter sized splinters from
asteroids and orbit in the
ecliptic plane of the planets.
Pictured above from last year is one of the more spectacular pictures of
the gegenschein yet taken.
Here a deep exposure of an extremely dark sky over
Las Campanas Observatory in
the gegenschein so clearly that even a surrounding glow is visible.
objects include the
the Pleiades star cluster,
the California Nebula,
the belt of Orion just below the
Orion Nebula and inside
Barnard's Loop, and
bright stars Sirius and
is distinguished from zodiacal light near the Sun by the
high angle of reflection.
During the day, a phenomenon similar to
the gegenschein called the glory can
be seen in reflecting air or clouds opposite the Sun from an airplane.
(Las Campanas Observatory,