The Zodiacal Light and the Gegenschein

[Weather-history]

We are at the time of the year, when we have the best opportuntity to see the zodiacal light.

The zodiacal light is a glow that is wedged shape that rises along the ecliptic or the zodiac, hence the name. It is caused by sunlight reflecting off the millions of particles of space debris and dust that are most concentrated in the plane of the solar system.

The best time to see this glow is in the spring and autumn because the ecliptic is at its most vertical to the horizon. In the springtime, the zodiac light can be seen as soon as evening astronomical twilight has ended in the western sky and in autumntime, in the eastern sky in the predawn sky.

Sadly, to see the light, you will need a clear horizon, clear transparent skies, a moonless night and no light pollution. So with these preconditions, opportunties are limited.

A photo of the zodiacal light

http://www.astronomija.com.mk/images/uploa...iacal_light.jpg

The gegenschein is an even more elusive phenomenon. It is produced in the same way as the zodiacal light, by sunlight reflecting off interplanetary dust and debris except it is reflected directly back to the sun and so the small oval shape glow is directly opposite to the sun in the sky ie. the position of the gegenschein in the sky is 180 degrees to the positon of the sun.

Again you will need clear skies, no moon, away from the Milky Way and no light pollution. Patrick Moore has only seen it once in this country and that was in the 1940s.

A photo of the gegenschein

http://webs.uvigo.es/sli/xermanismos/Glosa...os/image013.jpg

Edited October 11, 2006 by Mr_Data

[VillagePlank]

Great post Mr D

[stella]

Yes, I spotted the Zodiacal light in the morning sky about a

month ago. It was nicely aligned along the Regulus-Saturn

direction. 30 years ago I saw the Zodiacal band from Australia,

stretching right across the sky. However, I was unable to detect the gegenschein since it was positioned directly in front of the Milky Way.

Amazing that the Milky Way was causing light pollution!