Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 1739
| Start | August 25, 1983 at 05:41 AM UTC |
|---|---|
| End | September 21, 1983 at 11:55 AM UTC |
| Length (days) | 27.26 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 1734 | April 11, 1983 at 03:19 AM UTC | May 8, 1983 at 09:20 AM UTC | 27.25 |
| 1735 | May 8, 1983 at 09:20 AM UTC | June 4, 1983 at 02:27 PM UTC | 27.21 |
| 1736 | June 4, 1983 at 02:27 PM UTC | July 1, 1983 at 07:10 PM UTC | 27.20 |
| 1737 | July 1, 1983 at 07:10 PM UTC | July 29, 1983 at 12:07 AM UTC | 27.21 |
| 1738 | July 29, 1983 at 12:07 AM UTC | August 25, 1983 at 05:41 AM UTC | 27.23 |
| 1739 | August 25, 1983 at 05:41 AM UTC | September 21, 1983 at 11:55 AM UTC | 27.26 |
| 1740 | September 21, 1983 at 11:55 AM UTC | October 18, 1983 at 06:44 PM UTC | 27.28 |
| 1741 | October 18, 1983 at 06:44 PM UTC | November 15, 1983 at 01:57 AM UTC | 27.30 |
| 1742 | November 15, 1983 at 01:57 AM UTC | December 12, 1983 at 09:31 AM UTC | 27.32 |
| 1743 | December 12, 1983 at 09:31 AM UTC | January 8, 1984 at 05:28 PM UTC | 27.33 |
| 1744 | January 8, 1984 at 05:28 PM UTC | February 5, 1984 at 01:39 AM UTC | 27.34 |
About this tool
A Carrington rotation is the time the Sun takes to turn once on its axis as seen from the Earth: 27.2753 days on average. The count was defined by the English astronomer Richard Carrington, who studied sunspots in the 1850s; rotation 1 began on 9 November 1853, and the numbering has run without interruption since.
Explorer computes the start of each rotation with the formula given by Jean Meeus in Astronomical Algorithms (chapter 29), implemented in its own astronomy library and checked against published dates. A rotation begins when the Carrington longitude L₀ of the central meridian passes through 0°; because the Earth moves along its orbit, the synodic period varies slightly around the mean, hence lengths of 27.2 to 27.3 days.
Observers use the rotation number as a calendar for the Sun: an active region that crosses the disc reappears about one rotation later, and the community activity heatmap shows one row per rotation so that returning regions line up. Enter a date to find its rotation, or a number to get the UTC start and end dates and the neighbouring rotations.