By far the most common enquiry we have is for the time of sunrise and sunset on a particular day at a particular location. These links point to the sites that we use to obtain this information. We include a brief explanation of how to obtain sunrise/set information from the selected links. These links will also be useful for moon phases, moonrise/set times and other information regarding the sun and moon
Sun or Moon Rise/Set Tables for One Year. Provided by the
US Naval Observatory, this is the easiest way to get rise or set
times off the web. A guide on how to use this service is given
below.
The
Astrodienst Atlas Database. Actually part of an astrology
site, this page enables you to search for the latitudes and
longitudes for over quarter of a million towns worldwide. A particularly useful resource.
The World Clock
Timezone Database gives you local time in many of the
world's largest cities. Contains useful information on daylight
saving time conventions, timezones and more.
Moon Phase Calendar. Shows you what the moon looks like on every day of every month.
Fraction of the Moon illuminated Calculate the illuminated fraction of the moon for the years 1700 - 2100
Islamic Moon-Sighting Calculations. A page maintained by and for
members of the Islamic community. Contains detail of upcoming
events in the Islamic calendar.
USNO Astronomical Applications. The best site on the web for obtaining ephemerides of the Sun and moon, plus much more.
USNO WebMICA An excellent application from USNO for calculating the positions of the sun, moon and planets in the sky from any location (select "Apparent coordinates: topocentric Alt & Az, wrt local horizon").
Variation in Time of Sunrise. An essay detailing the mathematical calculation
of sunrise and sunset times. For the keen.
Times of the Earth's Perihelion and Aphelion 1992-2005. Includes date and times of the Equinoxes and
Solstices. Another part of the US Naval Observatory's marvellous data service whose front end is here...
Since rise and set times for the sun and moon are such a popular request for us, it is worth mentioning a few tips on the subject:
Obtain the Latitude and longitude.
The times or rise and set of astronomical objects depend on your location. From a good atlas, or something like the the Astrodienst Atlas Database, make a note of the latitude and longitude of the town or city nearest to you. You don't have to be too accurate - the difference in times between two places even 20 or so miles apart is never more than a couple of minutes. Latitude and longitude are normally quoted in degrees and minutes (e.g N56 25 means North 56 degrees and 25 minutes - NOT 56 and a quarter degrees). Make sure you know what you have and what you need. The USNO software (Mica) that we recommend above, requires its input in degrees and minutes.
Work out the timezone.
Rise and set times are normally given in GMT or Universal time (the same thing). Be aware that the place you have calculated the times for may sit a long way to the east or west of the Greenwich Meridian. If so then you will need to add (if to the west) or subtract (if to the east) the appropriate time difference. The World Clock Timezone Database tells you the offsets from Greenwich for a number of different cities. Again, a good atlas should contain the same information.
Don't forget Summer Time.
During summer months many countries observe Daylight Saving Time. The DST offset is usually +1 hour from GMT. If your rise and set times are GMT make sure you add one hour to get the correct "local" times. The The World Clock Timezone Database has the dates when DST begins and ends for major cities worldwide. The Royal Greenwich Observatory produces an information leaflet which discusses the letter of the law for DST in the UK over the past few decades.
Lighting up time.
Sunrise and sunset times are NOT the same as lighting up times. Street lamps in the UK are generally come on about half an hour after sunset and turn off about half an hour prior to sunrise.
Hours of Darkness.
When the sun goes down and when it actually gets dark are not always the same thing - particularly for northerly or southerly latitudes. Civil twilight is, as a rule of thumb, the time when it becomes too dark to perform detailed operations outdoors without artificial lighting. The brightest stars and planets are visible at this time. Civil, nautical and astronomical twilight times can be calculated using the USNO software.
