Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 7913
| Start | September 13, 2444 at 12:09 PM UTC |
|---|---|
| End | October 10, 2444 at 06:41 PM UTC |
| Length (days) | 27.27 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 7908 | April 30, 2444 at 09:54 AM UTC | May 27, 2444 at 03:27 PM UTC | 27.23 |
| 7909 | May 27, 2444 at 03:27 PM UTC | June 23, 2444 at 08:18 PM UTC | 27.20 |
| 7910 | June 23, 2444 at 08:18 PM UTC | July 21, 2444 at 01:04 AM UTC | 27.20 |
| 7911 | July 21, 2444 at 01:04 AM UTC | August 17, 2444 at 06:16 AM UTC | 27.22 |
| 7912 | August 17, 2444 at 06:16 AM UTC | September 13, 2444 at 12:09 PM UTC | 27.25 |
| 7913 | September 13, 2444 at 12:09 PM UTC | October 10, 2444 at 06:41 PM UTC | 27.27 |
| 7914 | October 10, 2444 at 06:41 PM UTC | November 7, 2444 at 01:41 AM UTC | 27.29 |
| 7915 | November 7, 2444 at 01:41 AM UTC | December 4, 2444 at 09:04 AM UTC | 27.31 |
| 7916 | December 4, 2444 at 09:04 AM UTC | December 31, 2444 at 04:49 PM UTC | 27.32 |
| 7917 | December 31, 2444 at 04:49 PM UTC | January 28, 2445 at 12:54 AM UTC | 27.34 |
| 7918 | January 28, 2445 at 12:54 AM UTC | February 24, 2445 at 09:05 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.