Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 1448
| Start | December 1, 1961 at 04:28 AM UTC |
|---|---|
| End | December 28, 1961 at 12:16 PM UTC |
| Length (days) | 27.33 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 1443 | July 17, 1961 at 08:04 PM UTC | August 14, 1961 at 01:21 AM UTC | 27.22 |
| 1444 | August 14, 1961 at 01:21 AM UTC | September 10, 1961 at 07:21 AM UTC | 27.25 |
| 1445 | September 10, 1961 at 07:21 AM UTC | October 7, 1961 at 01:58 PM UTC | 27.28 |
| 1446 | October 7, 1961 at 01:58 PM UTC | November 3, 1961 at 09:02 PM UTC | 27.29 |
| 1447 | November 3, 1961 at 09:02 PM UTC | December 1, 1961 at 04:28 AM UTC | 27.31 |
| 1448 | December 1, 1961 at 04:28 AM UTC | December 28, 1961 at 12:16 PM UTC | 27.33 |
| 1449 | December 28, 1961 at 12:16 PM UTC | January 24, 1962 at 08:24 PM UTC | 27.34 |
| 1450 | January 24, 1962 at 08:24 PM UTC | February 21, 1962 at 04:33 AM UTC | 27.34 |
| 1451 | February 21, 1962 at 04:33 AM UTC | March 20, 1962 at 12:17 PM UTC | 27.32 |
| 1452 | March 20, 1962 at 12:17 PM UTC | April 16, 1962 at 07:07 PM UTC | 27.28 |
| 1453 | April 16, 1962 at 07:07 PM UTC | May 14, 1962 at 12:54 AM UTC | 27.24 |
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.