Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 2497
| Start | April 2, 2040 at 03:19 AM UTC |
|---|---|
| End | April 29, 2040 at 09:41 AM UTC |
| Length (days) | 27.26 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 2492 | November 17, 2039 at 12:10 PM UTC | December 14, 2039 at 07:46 PM UTC | 27.32 |
| 2493 | December 14, 2039 at 07:46 PM UTC | January 11, 2040 at 03:45 AM UTC | 27.33 |
| 2494 | January 11, 2040 at 03:45 AM UTC | February 7, 2040 at 11:56 AM UTC | 27.34 |
| 2495 | February 7, 2040 at 11:56 AM UTC | March 5, 2040 at 07:57 PM UTC | 27.33 |
| 2496 | March 5, 2040 at 07:57 PM UTC | April 2, 2040 at 03:19 AM UTC | 27.31 |
| 2497 | April 2, 2040 at 03:19 AM UTC | April 29, 2040 at 09:41 AM UTC | 27.26 |
| 2498 | April 29, 2040 at 09:41 AM UTC | May 26, 2040 at 03:02 PM UTC | 27.22 |
| 2499 | May 26, 2040 at 03:02 PM UTC | June 22, 2040 at 07:49 PM UTC | 27.20 |
| 2500 | June 22, 2040 at 07:49 PM UTC | July 20, 2040 at 12:38 AM UTC | 27.20 |
| 2501 | July 20, 2040 at 12:38 AM UTC | August 16, 2040 at 05:59 AM UTC | 27.22 |
| 2502 | August 16, 2040 at 05:59 AM UTC | September 12, 2040 at 12:01 PM UTC | 27.25 |
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.