Friday, August 22, 2008
When Can You First See Venus (Part 2)
Jupiter was visible 10 minutes after Sunset, but it was probably visible earlier, as the eastern sky was basically blotted out by cloud until then. Also, as the eastern sky is darker than the western sky at sunset, Jupiter should be visible earlier.
There should be some sort of formula that relates sky brightness to time after sunset, that way you could calculate when a planet or star would appear based on their brightness. However, my current web searches have not found one. I can't even get a figure for daytime sky brightness that I can relate to magnitude. If anyone knows one, please let me know.