Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 4211
| Start | March 31, 2168 at 09:12 PM UTC |
|---|---|
| End | April 28, 2168 at 03:42 AM UTC |
| Length (days) | 27.27 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 4206 | November 16, 2167 at 06:00 AM UTC | December 13, 2167 at 01:33 PM UTC | 27.31 |
| 4207 | December 13, 2167 at 01:33 PM UTC | January 9, 2168 at 09:29 PM UTC | 27.33 |
| 4208 | January 9, 2168 at 09:29 PM UTC | February 6, 2168 at 05:39 AM UTC | 27.34 |
| 4209 | February 6, 2168 at 05:39 AM UTC | March 4, 2168 at 01:44 PM UTC | 27.34 |
| 4210 | March 4, 2168 at 01:44 PM UTC | March 31, 2168 at 09:12 PM UTC | 27.31 |
| 4211 | March 31, 2168 at 09:12 PM UTC | April 28, 2168 at 03:42 AM UTC | 27.27 |
| 4212 | April 28, 2168 at 03:42 AM UTC | May 25, 2168 at 09:10 AM UTC | 27.23 |
| 4213 | May 25, 2168 at 09:10 AM UTC | June 21, 2168 at 02:00 PM UTC | 27.20 |
| 4214 | June 21, 2168 at 02:00 PM UTC | July 18, 2168 at 06:47 PM UTC | 27.20 |
| 4215 | July 18, 2168 at 06:47 PM UTC | August 15, 2168 at 12:02 AM UTC | 27.22 |
| 4216 | August 15, 2168 at 12:02 AM UTC | September 11, 2168 at 05:58 AM UTC | 27.25 |
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.