Calculating Sunrise, Sunset and Lighting Up Times

There are a number of websites online that provide free information about sunrise and sunset times for previous dates across the world. See below for some examples and for further information or if you require an official report from the Observatory please contact dunsink@dias.ie.

Major cities

Use timeanddate.com/sun for major town/city information. Simply enter your location at the top of the page, e.g., type your location (e.g., ‘Dublin’) and hit enter to see the relevant information for that location over the past two decades.

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Latitude/longitude

Try suncalc.org if you need information related to a specific latitude and longitude location rather than a general city area. Input the geodata for the selected location on the left hand side, as well as the relevant date and time. Alternatively drag the locator on the main map to select the location. Solar data will then appear for this location on the left.

SunCalc also has an API service! Read more information about it here. The code below shows the link attributes used and resulting weblink for the above example:

https://suncalc.org/#/lat,lon,zoom/date/time/objectlevel/maptype

https://suncalc.org/#/53.388,-6.3371,16/2021.08.01/12:00/1/0

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Realtime information

If you want information about what time the next sunset/sunrise might be at your location, the quickest way is probably to search google.com! For example simply typing ‘sunset Dublin’ yields the below search result for today’s date:

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Lighting up times

Lighting up hours are defined as “the period commencing one half-hour after sunset on any day and expiring one half-hour before sunrise on the next day” as per Road Traffic (Lighting of Vehicles) Regulations, 1963.