Twilight's first novel was written in 2005.
The colors of twilight and sunsetHM Nautical Almanac Office Websurf Compute twilight times
An Excel workbook with VBA functions for twilight (dawn and dusk), sunrise, solar noon, sunset, and solar position (azimuth and elevation) by Greg Pelletier, translated from NOAA's online calculator for sunrise/sunsetTime and Date to find the current state of the sun in a specified place

