Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 8667
| Start | January 4, 2501 at 03:05 AM UTC |
|---|---|
| End | January 31, 2501 at 11:11 AM UTC |
| Length (days) | 27.34 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 8662 | August 20, 2500 at 04:22 PM UTC | September 16, 2500 at 10:18 PM UTC | 27.25 |
| 8663 | September 16, 2500 at 10:18 PM UTC | October 14, 2500 at 04:52 AM UTC | 27.27 |
| 8664 | October 14, 2500 at 04:52 AM UTC | November 10, 2500 at 11:54 AM UTC | 27.29 |
| 8665 | November 10, 2500 at 11:54 AM UTC | December 7, 2500 at 07:18 PM UTC | 27.31 |
| 8666 | December 7, 2500 at 07:18 PM UTC | January 4, 2501 at 03:05 AM UTC | 27.32 |
| 8667 | January 4, 2501 at 03:05 AM UTC | January 31, 2501 at 11:11 AM UTC | 27.34 |
| 8668 | January 31, 2501 at 11:11 AM UTC | February 27, 2501 at 07:21 PM UTC | 27.34 |
| 8669 | February 27, 2501 at 07:21 PM UTC | March 27, 2501 at 03:08 AM UTC | 27.32 |
| 8670 | March 27, 2501 at 03:08 AM UTC | April 23, 2501 at 10:04 AM UTC | 27.29 |
| 8671 | April 23, 2501 at 10:04 AM UTC | May 20, 2501 at 03:56 PM UTC | 27.24 |
| 8672 | May 20, 2501 at 03:56 PM UTC | June 16, 2501 at 08:57 PM UTC | 27.21 |
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.