The almanac module provides twilight times, sunrise/set and moonrise/set data for any location. This can be a useful addition to sites that include astronomy, religious, education, energy-related, weather, or astrology information. Sites devoted to a range of outdoor activities, from night photography to fishing, can also benefit from adding an almanac.
While using PHP V5 sunrise and sunset functions ease the display of sunrise/sunset times, calculating the time of the rising and setting of the moon is more complex. The problems of calculating moonrise and moonset - such as parallax, refraction, and accounting for days when there is either no moonrise or moonset - have been given exhaustive treatment elsewhere (just do a Google search on moonrise calculations.) The almanac module implements the low resolution method for calculating moonrise and moonset outlined in Montenbruck and Pfleger's Astronomy on the Personal Computer (1989).
The location data for the module is controlled via the settings page. The module outputs a simple themable block that display's the current location date and time, as well as sunrise/set and moonrise/set times. It also outputs a themable page that includes rise and set times for astronomical twilight, nautical twilight, and civil twilight.
PHP V5 is required, The drupal 6 version requires the Date API module.
A special thank you to Alan D for his work in upgrading the code to drupal 7 and adding some great new functionality.