Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 4465
| Start | March 20, 2187 at 06:44 PM UTC |
|---|---|
| End | April 17, 2187 at 01:42 AM UTC |
| Length (days) | 27.29 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 4460 | November 4, 2186 at 03:30 AM UTC | December 1, 2186 at 10:54 AM UTC | 27.31 |
| 4461 | December 1, 2186 at 10:54 AM UTC | December 28, 2186 at 06:40 PM UTC | 27.32 |
| 4462 | December 28, 2186 at 06:40 PM UTC | January 25, 2187 at 02:45 AM UTC | 27.34 |
| 4463 | January 25, 2187 at 02:45 AM UTC | February 21, 2187 at 10:56 AM UTC | 27.34 |
| 4464 | February 21, 2187 at 10:56 AM UTC | March 20, 2187 at 06:44 PM UTC | 27.33 |
| 4465 | March 20, 2187 at 06:44 PM UTC | April 17, 2187 at 01:42 AM UTC | 27.29 |
| 4466 | April 17, 2187 at 01:42 AM UTC | May 14, 2187 at 07:35 AM UTC | 27.25 |
| 4467 | May 14, 2187 at 07:35 AM UTC | June 10, 2187 at 12:38 PM UTC | 27.21 |
| 4468 | June 10, 2187 at 12:38 PM UTC | July 7, 2187 at 05:22 PM UTC | 27.20 |
| 4469 | July 7, 2187 at 05:22 PM UTC | August 3, 2187 at 10:21 PM UTC | 27.21 |
| 4470 | August 3, 2187 at 10:21 PM UTC | August 31, 2187 at 03:59 AM UTC | 27.23 |
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.