Solar Position Calculator
Please note that this web page is the old version of the NOAA Solar Calculator. Back when this calculator was first created, we decided to use a non-standard definition of longitude and time zone, to make coordinate entry less awkward. So on this page, both longitude and time zone are defined as positive to the west, instead of the international standard of positive to the east of the Prime Meridian.
We maintain this page as a courtesy to those people who, for whatever reason, prefer the old calculator. For the rest of you, we encourage you to instead click here to try the updated version of NOAA's Solar Calculator
Latitude and Longitude can be in deg/min/sec, or decimal degrees entered in the "Deg:" field. (If you enter decimal degrees in the degrees field, please clear the minutes and seconds fields, or they will be added in.) If you select a city from the pulldown menu, the latitude, longitude and time zone fields will be filled in by the program. If you want to input latitude, longitude or time zone manually, be sure to select "Enter Lat/Long -->" from the City pulldown box, or your numbers will be overwritten by the selected city's location.
You can enter a different time zone for a location by selecting "Enter Lat/Long -->" in the City pulldown box. Otherwise the time zone associated with the selected city's Local Standard Time will be automatically entered. Selecting "Yes" in the Daylight Saving field will cause the solar position calculation to assume the current time has been adjusted forward one hour from standard time. If you are uncertain of the time zone for a location, refer to our Time Zone Table.
The program retrieves the current date and time from your computer, and fills in these values in the date/time fields. To perform calculations for a different date, simply select the month in the pulldown box, and enter the day and four digit year in the appropriate input boxes. Time of day for the calculation can be changed in the same way.
Hit the "Calculate Solar Position" button. Once the calculations are complete, you may use your browser's "Print" function to obtain a hardcopy of the results. Results are given in the following units: Equation of Time in minutes of time; Solar Declination in degrees, with positive to the north; Azimuth in degrees clockwise from north; Elevation in degrees up from the horizon; Cosine of Solar Zenith Angle is unitless.
Note that for latitudes greater than 72° north or less than 72° south, accuracy may be lower due in part to the effects of atmospheric refraction.
Solar Calculator Links
Time Zone Table
Solar Calculator Glossary
Back to SRRB Homepage