Twilight Zones

This chart shows the relationship between the angular elevation of the sun relative to the horizon and levels of twilight. The values are for the 24 hours between 1pm BST 12th August 2010 and 1pm BST 13th August 2010, and for the location Brighton in East Sussex (50.8° N 0.1° W). In equatorial regions, night and day breaks very much more quickly. In Brighton on this late summer day, sunset to full darkness took 2 hours and 22 minutes. By comparison, in Singapore (near the equator) the process took 1 hour 11 minutes.

A full listing of data for the two nights Dominic Alves tried to photograph Perseid meteors is at the foot of this description.

via Dominic Alves