Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 2550
| Start | March 17, 2044 at 05:06 PM UTC |
|---|---|
| End | April 14, 2044 at 12:03 AM UTC |
| Length (days) | 27.29 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 2545 | November 2, 2043 at 01:52 AM UTC | November 29, 2043 at 09:15 AM UTC | 27.31 |
| 2546 | November 29, 2043 at 09:15 AM UTC | December 26, 2043 at 05:01 PM UTC | 27.32 |
| 2547 | December 26, 2043 at 05:01 PM UTC | January 23, 2044 at 01:07 AM UTC | 27.34 |
| 2548 | January 23, 2044 at 01:07 AM UTC | February 19, 2044 at 09:18 AM UTC | 27.34 |
| 2549 | February 19, 2044 at 09:18 AM UTC | March 17, 2044 at 05:06 PM UTC | 27.33 |
| 2550 | March 17, 2044 at 05:06 PM UTC | April 14, 2044 at 12:03 AM UTC | 27.29 |
| 2551 | April 14, 2044 at 12:03 AM UTC | May 11, 2044 at 05:57 AM UTC | 27.25 |
| 2552 | May 11, 2044 at 05:57 AM UTC | June 7, 2044 at 10:59 AM UTC | 27.21 |
| 2553 | June 7, 2044 at 10:59 AM UTC | July 4, 2044 at 03:43 PM UTC | 27.20 |
| 2554 | July 4, 2044 at 03:43 PM UTC | July 31, 2044 at 08:43 PM UTC | 27.21 |
| 2555 | July 31, 2044 at 08:43 PM UTC | August 28, 2044 at 02:21 AM UTC | 27.23 |
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.