The Gegenschein
(GAY-guhn-shine) was easy to see tonight. It is to the left of M45 above Aries. I think its size is nearly 30 by 15 degrees.
"Like the
zodiacal light the gegenschein is sunlight reflected by
interplanetary dust. Most of this dust is orbiting the sun in about the ecliptic plane (
zodiac). It is distinguished from zodiacal light by its high angle of reflection of the incident sunlight on the dust particles. It forms a slightly more luminous,
oval glow directly opposite the Sun within the band of luminous zodiacal light. The intensity of gegenschein is (relatively) enhanced because (a) each dust particle is seen in full
phase, and (b) the
backscattering geometry leads to constructive interference."
http://en.wikipedia.org/wiki/Gegenschein