The good news about being stuck on this planet is that we have air to breath. The bad news for astrophotography is that all that air is not heated uniformly and it moves around a lot. That creates a lot of refraction effects, i.e., the light doesn't follow a straight path due to the varying index of refraction of the various air "cells" in the upper atmosphere. That tends to make things twinkle and dance around. On a photographic image, the stars appear larger than they should and detail in deep-sky objects gets fuzzed up a little. To really see how extreme this can get, look at a bright star through the fumes of a really hot campfire some time. I looked at Venus through campfire fumes when Venus was very bright. It looked like a fuzzball with hundreds of little bright spikes emanating from the center. The effect was very striking.

There are times when the atmosphere settles down however and "seeing" is good. That is when one can begin to see surface detail on Mars for example. It is the best time to take astrophotographs also. Some say the best seeing occurs when a stable High Pressure system is positioned above you. Some say it often occurs shortly after dusk. Some say to stay upwind of mountain peaks.

I do know that good "seeing" does not occur every night. When it does occur I have been able to visually see both components of Zeta Cancri with black space in between and diffraction rings dancing around the components. This was with a 4.7 mm eyepiece which ran the scope magnification up to 532 power. The Zeta Cancri components are separated by .6 Arc-Seconds. The Meade specs for my telescope claim .45 Arc-Second resolution. The Zeta Cancri observation verifies that the telescope meets the advertised specs and that makes me happy.

Copyright 1997, 1998, 1999, 2000 Howard C. Anderson