Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 1370
| Start | February 3, 1956 at 08:31 PM UTC |
|---|---|
| End | March 2, 1956 at 04:35 AM UTC |
| Length (days) | 27.34 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 1365 | September 20, 1955 at 06:51 AM UTC | October 17, 1955 at 01:38 PM UTC | 27.28 |
| 1366 | October 17, 1955 at 01:38 PM UTC | November 13, 1955 at 08:50 PM UTC | 27.30 |
| 1367 | November 13, 1955 at 08:50 PM UTC | December 11, 1955 at 04:24 AM UTC | 27.32 |
| 1368 | December 11, 1955 at 04:24 AM UTC | January 7, 1956 at 12:20 PM UTC | 27.33 |
| 1369 | January 7, 1956 at 12:20 PM UTC | February 3, 1956 at 08:31 PM UTC | 27.34 |
| 1370 | February 3, 1956 at 08:31 PM UTC | March 2, 1956 at 04:35 AM UTC | 27.34 |
| 1371 | March 2, 1956 at 04:35 AM UTC | March 29, 1956 at 12:02 PM UTC | 27.31 |
| 1372 | March 29, 1956 at 12:02 PM UTC | April 25, 1956 at 06:30 PM UTC | 27.27 |
| 1373 | April 25, 1956 at 06:30 PM UTC | May 22, 1956 at 11:57 PM UTC | 27.23 |
| 1374 | May 22, 1956 at 11:57 PM UTC | June 19, 1956 at 04:46 AM UTC | 27.20 |
| 1375 | June 19, 1956 at 04:46 AM UTC | July 16, 1956 at 09:33 AM 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.