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Clear moonless nights during late February are the best times to look for Gegenschein and Zodiacal Light. Each is a thin veil of light hovering on the ecliptic like an indecisive ghost not ready to depart this life, yet finding no reason to stay. They are caused by sunlight reflecting off of meteoric dust lying along the plane of the solar system, extending far out beyond our Earth.
Zodiacal Light is roughly triangular, and points away from the Sun. Its spectrum is the same as the solar spectrum, reinforcing the notion that it is sunlight reflecting off meteoric dust in the plane of the solar system. Because the ecliptic is nearly perpendicular to the horizon at this time, the Zodiacal Light extends more nearly vertically from the horizon, affording us a better opportunity to see it after sunset. During most months, the angle of the ecliptic relative to our horizon is so small, any Zodiacal Light would be lost in the dusty filth of our atmosphere. Zodiacal Light might also be observed a couple of hours before dawn, along the ecliptic in the eastern sky. Seen at this ungodly, predawn hour, it is often referred to as the False Dawn. The Gegenschein is a faint blob of light in the sky and, like the Zodiacal Light, its spectrum is identical to that of Sun, which again suggests it is sunlight reflected off meteoric dust. It is very faint, fainter even than the Milky Way, so the intrusion of any additional light from the Moon or street lights, a nearby planet or the tiniest bit of haze makes it impossible to see this faint ghost of a glow. It has been reported that, under the very best viewing conditions, the Zodiacal Light has been observed extending all the way up to the Gegenschein (or vice versa, if you prefer.) Similarly, a glow was observed in the direction of the Leonid radiant during Leonid storm activity in the 1800's. This was sunlight reflected off the dust cloud of Leonid meteoric particles. While Mercury is incognito, in absentia and persona no gratis this month, Venus is giving its best evening performance in its cycle of 8-year appearances. It sets about 3 and ½ hours after the sun by the end of the month; it gets even better in March and April. Watch for a skinny waxing crescent moon to pass by Venus on the evening of the 23rd. A little fatter, it will pass even nearer Mars on the 25th. Go To Page: 1 2
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