Rich: Were you able to see more than the usual bright tiangular shape above the horizon, i.e. across the entire sky and/or the Geggenshein? -----Original Message----- From: utah-astronomy-bounces+kimharch=cut.net@mailman.xmission.com [mailto:utah-astronomy-bounces+kimharch=cut.net@mailman.xmission.com] On Behalf Of Richard Tenney Sent: Tuesday, August 22, 2006 3:19 PM To: Utah Astronomy Subject: RE: [Utah-astronomy] Zodiacal light I really saw it, or at least recognized it as such, for the first time while out in the West Desert in the Spring of '05 with several others, about an hour or so after sunset; very cool phenomenon. --- Kim <kimharch@cut.net> wrote:
Hi Joe. The ZL generally occurs along the ecliptic - it is brightest, however, in the inner solar system and is therefore more visible when the sun is not too far below the horizon. Where you see it depends on where the ecliptic intersects your horizon. This varies throughout the year, just as the points of sunrise and sunset change from the same observing point. The ZL is generally most visible when the following also occur:(1) When the ecliptic is at a relatively steep angle to the horizon, which occurs in the northern hemisphere in the evening hours in the spring and in the morning hours in the fall. (2) When skies are dark and transparent - it doesn't take much light pollution or moonlight to obscure the ZL. (3) When you're looking for it.
I think that because of (1) the "false dawn" is a year-round phenomon in equatorial regions. Can anyone confirm this? Also, there should be a corresponding "false evening twilight" that might last well after both civil and astronomical twilight have ended, but I've never heard of it described that way.
There's a good discussion of the ZL and Geggenshein in the Observer's Handbook published by the Royal Astronomical Society of Canada.
Kim
-----Original Message----- From:
utah-astronomy-bounces+kimharch=cut.net@mailman.xmission.com
[mailto:utah-astronomy-bounces+kimharch=cut.net@mailman.xmission.com]
On Behalf Of Joe Bauman Sent: Tuesday, August 22, 2006 2:46 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Zodiacal light
Kim, what direction is the ZL in? I once thought I saw it sort of to the south. Thanks, Joe
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