Gegenschein
Gegenschein (
German for
counterglow) is a faint brightening of the night sky in the region of the
zodiac directly opposite the
Sun caused by reflection of sunlight by small dust particles that lie in the plane of the
Solar system. It appears as a softly glowing oval region a few degrees wide and 10-15° in length, oriented along the plane of the
ecliptic. It is so faint that it cannot be seen if there is any
moonlight or if it falls in the vicinity of the
Milky Way.
The gegenschein is one of several skyglows that also include the zodiacal light and the zodiacal band.
See Optical phenomenon.