Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 1102
| Start | January 30, 1936 at 01:57 AM UTC |
|---|---|
| End | February 26, 1936 at 10:04 AM UTC |
| Length (days) | 27.34 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 1097 | September 15, 1935 at 12:34 PM UTC | October 12, 1935 at 07:17 PM UTC | 27.28 |
| 1098 | October 12, 1935 at 07:17 PM UTC | November 9, 1935 at 02:25 AM UTC | 27.30 |
| 1099 | November 9, 1935 at 02:25 AM UTC | December 6, 1935 at 09:55 AM UTC | 27.31 |
| 1100 | December 6, 1935 at 09:55 AM UTC | January 2, 1936 at 05:48 PM UTC | 27.33 |
| 1101 | January 2, 1936 at 05:48 PM UTC | January 30, 1936 at 01:57 AM UTC | 27.34 |
| 1102 | January 30, 1936 at 01:57 AM UTC | February 26, 1936 at 10:04 AM UTC | 27.34 |
| 1103 | February 26, 1936 at 10:04 AM UTC | March 24, 1936 at 05:40 PM UTC | 27.32 |
| 1104 | March 24, 1936 at 05:40 PM UTC | April 21, 1936 at 12:19 AM UTC | 27.28 |
| 1105 | April 21, 1936 at 12:19 AM UTC | May 18, 1936 at 05:55 AM UTC | 27.23 |
| 1106 | May 18, 1936 at 05:55 AM UTC | June 14, 1936 at 10:48 AM UTC | 27.20 |
| 1107 | June 14, 1936 at 10:48 AM UTC | July 11, 1936 at 03:33 PM UTC | 27.20 |
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.