Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 6546
| Start | August 15, 2342 at 07:08 AM UTC |
|---|---|
| End | September 11, 2342 at 12:59 PM UTC |
| Length (days) | 27.24 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 6541 | April 1, 2342 at 04:05 AM UTC | April 28, 2342 at 10:44 AM UTC | 27.28 |
| 6542 | April 28, 2342 at 10:44 AM UTC | May 25, 2342 at 04:20 PM UTC | 27.23 |
| 6543 | May 25, 2342 at 04:20 PM UTC | June 21, 2342 at 09:13 PM UTC | 27.20 |
| 6544 | June 21, 2342 at 09:13 PM UTC | July 19, 2342 at 01:58 AM UTC | 27.20 |
| 6545 | July 19, 2342 at 01:58 AM UTC | August 15, 2342 at 07:08 AM UTC | 27.22 |
| 6546 | August 15, 2342 at 07:08 AM UTC | September 11, 2342 at 12:59 PM UTC | 27.24 |
| 6547 | September 11, 2342 at 12:59 PM UTC | October 8, 2342 at 07:28 PM UTC | 27.27 |
| 6548 | October 8, 2342 at 07:28 PM UTC | November 5, 2342 at 02:28 AM UTC | 27.29 |
| 6549 | November 5, 2342 at 02:28 AM UTC | December 2, 2342 at 09:49 AM UTC | 27.31 |
| 6550 | December 2, 2342 at 09:49 AM UTC | December 29, 2342 at 05:33 PM UTC | 27.32 |
| 6551 | December 29, 2342 at 05:33 PM UTC | January 26, 2343 at 01:37 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.