Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 3571
| Start | June 15, 2120 at 03:00 PM UTC |
|---|---|
| End | July 12, 2120 at 07:45 PM UTC |
| Length (days) | 27.20 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 3566 | January 31, 2120 at 05:57 AM UTC | February 27, 2120 at 02:05 PM UTC | 27.34 |
| 3567 | February 27, 2120 at 02:05 PM UTC | March 25, 2120 at 09:44 PM UTC | 27.32 |
| 3568 | March 25, 2120 at 09:44 PM UTC | April 22, 2120 at 04:26 AM UTC | 27.28 |
| 3569 | April 22, 2120 at 04:26 AM UTC | May 19, 2120 at 10:06 AM UTC | 27.24 |
| 3570 | May 19, 2120 at 10:06 AM UTC | June 15, 2120 at 03:00 PM UTC | 27.20 |
| 3571 | June 15, 2120 at 03:00 PM UTC | July 12, 2120 at 07:45 PM UTC | 27.20 |
| 3572 | July 12, 2120 at 07:45 PM UTC | August 9, 2120 at 12:52 AM UTC | 27.21 |
| 3573 | August 9, 2120 at 12:52 AM UTC | September 5, 2120 at 06:41 AM UTC | 27.24 |
| 3574 | September 5, 2120 at 06:41 AM UTC | October 2, 2120 at 01:08 PM UTC | 27.27 |
| 3575 | October 2, 2120 at 01:08 PM UTC | October 29, 2120 at 08:06 PM UTC | 27.29 |
| 3576 | October 29, 2120 at 08:06 PM UTC | November 26, 2120 at 03:26 AM UTC | 27.31 |
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.