Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 1360
| Start | May 7, 1955 at 04:17 AM UTC |
|---|---|
| End | June 3, 1955 at 09:25 AM UTC |
| Length (days) | 27.21 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 1355 | December 21, 1954 at 03:00 PM UTC | January 17, 1955 at 11:04 PM UTC | 27.34 |
| 1356 | January 17, 1955 at 11:04 PM UTC | February 14, 1955 at 07:15 AM UTC | 27.34 |
| 1357 | February 14, 1955 at 07:15 AM UTC | March 13, 1955 at 03:08 PM UTC | 27.33 |
| 1358 | March 13, 1955 at 03:08 PM UTC | April 9, 1955 at 10:14 PM UTC | 27.30 |
| 1359 | April 9, 1955 at 10:14 PM UTC | May 7, 1955 at 04:17 AM UTC | 27.25 |
| 1360 | May 7, 1955 at 04:17 AM UTC | June 3, 1955 at 09:25 AM UTC | 27.21 |
| 1361 | June 3, 1955 at 09:25 AM UTC | June 30, 1955 at 02:09 PM UTC | 27.20 |
| 1362 | June 30, 1955 at 02:09 PM UTC | July 27, 1955 at 07:05 PM UTC | 27.21 |
| 1363 | July 27, 1955 at 07:05 PM UTC | August 24, 1955 at 12:37 AM UTC | 27.23 |
| 1364 | August 24, 1955 at 12:37 AM UTC | September 20, 1955 at 06:51 AM UTC | 27.26 |
| 1365 | September 20, 1955 at 06:51 AM UTC | October 17, 1955 at 01:38 PM UTC | 27.28 |
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.