# Sun almanac

The Sun's GHA and declination for every hour of UT, on any date from January 2, 2026 to December 30, 2028.

Loading the almanac…

## Reading the Sun's almanac

**GHA**, the Greenwich hour angle, is how far west of Greenwich the Sun's ground position is: it grows by about 15° every hour as the Earth turns. **Declination** is the ground position's latitude, north or south of the equator, and changes by at most about a minute of arc an hour.

The almanac lists both for each whole hour of UT. For the minutes and seconds between, add the **increment** to the GHA (the Sun moves 15° an hour, so 1° every four minutes), and correct the declination by **d**, its hourly change, in proportion. Enter a time above and the page shows that working.

The figures are computed from the JPL DE440 ephemeris and laid out as the Nautical Almanac's daily pages are.

It is a learning aid, not a navigation tool: at sea, use the official Nautical Almanac and tables, and check every position by other means.

## Learn to use it

- [Where the Sun is: GHA and declination](https://asterodos.com/m/almanac): the daily pages, increments and the d correction, with practice.
- [Angles, time and UT](https://asterodos.com/m/time): why the almanac runs on Greenwich time.
- [Sight reduction calculator](https://asterodos.com/sight-reduction-calculator): use the GHA and declination to reduce a sight.

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From Asterodos, a free interactive course in celestial navigation: https://asterodos.com/sun-almanac
For learning, not for navigating a vessel.