Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 9815
| Start | September 26, 2586 at 11:49 PM UTC |
|---|---|
| End | October 24, 2586 at 06:33 AM UTC |
| Length (days) | 27.28 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 9810 | May 13, 2586 at 09:22 PM UTC | June 10, 2586 at 02:35 AM UTC | 27.22 |
| 9811 | June 10, 2586 at 02:35 AM UTC | July 7, 2586 at 07:20 AM UTC | 27.20 |
| 9812 | July 7, 2586 at 07:20 AM UTC | August 3, 2586 at 12:13 PM UTC | 27.20 |
| 9813 | August 3, 2586 at 12:13 PM UTC | August 30, 2586 at 05:40 PM UTC | 27.23 |
| 9814 | August 30, 2586 at 05:40 PM UTC | September 26, 2586 at 11:49 PM UTC | 27.26 |
| 9815 | September 26, 2586 at 11:49 PM UTC | October 24, 2586 at 06:33 AM UTC | 27.28 |
| 9816 | October 24, 2586 at 06:33 AM UTC | November 20, 2586 at 01:43 PM UTC | 27.30 |
| 9817 | November 20, 2586 at 01:43 PM UTC | December 17, 2586 at 09:14 PM UTC | 27.31 |
| 9818 | December 17, 2586 at 09:14 PM UTC | January 14, 2587 at 05:08 AM UTC | 27.33 |
| 9819 | January 14, 2587 at 05:08 AM UTC | February 10, 2587 at 01:18 PM UTC | 27.34 |
| 9820 | February 10, 2587 at 01:18 PM UTC | March 9, 2587 at 09:24 PM 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.