Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 2330
| Start | October 12, 2027 at 09:19 PM UTC |
|---|---|
| End | November 9, 2027 at 04:27 AM UTC |
| Length (days) | 27.30 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 2325 | May 29, 2027 at 05:31 PM UTC | June 25, 2027 at 10:17 PM UTC | 27.20 |
| 2326 | June 25, 2027 at 10:17 PM UTC | July 23, 2027 at 03:08 AM UTC | 27.20 |
| 2327 | July 23, 2027 at 03:08 AM UTC | August 19, 2027 at 08:32 AM UTC | 27.22 |
| 2328 | August 19, 2027 at 08:32 AM UTC | September 15, 2027 at 02:38 PM UTC | 27.25 |
| 2329 | September 15, 2027 at 02:38 PM UTC | October 12, 2027 at 09:19 PM UTC | 27.28 |
| 2330 | October 12, 2027 at 09:19 PM UTC | November 9, 2027 at 04:27 AM UTC | 27.30 |
| 2331 | November 9, 2027 at 04:27 AM UTC | December 6, 2027 at 11:56 AM UTC | 27.31 |
| 2332 | December 6, 2027 at 11:56 AM UTC | January 2, 2028 at 07:48 PM UTC | 27.33 |
| 2333 | January 2, 2028 at 07:48 PM UTC | January 30, 2028 at 03:57 AM UTC | 27.34 |
| 2334 | January 30, 2028 at 03:57 AM UTC | February 26, 2028 at 12:05 PM UTC | 27.34 |
| 2335 | February 26, 2028 at 12:05 PM UTC | March 24, 2028 at 07:42 PM UTC | 27.32 |
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.