Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 2817
| Start | February 24, 2064 at 03:49 AM UTC |
|---|---|
| End | March 22, 2064 at 11:31 AM UTC |
| Length (days) | 27.32 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 2812 | October 10, 2063 at 01:10 PM UTC | November 6, 2063 at 08:15 PM UTC | 27.30 |
| 2813 | November 6, 2063 at 08:15 PM UTC | December 4, 2063 at 03:43 AM UTC | 27.31 |
| 2814 | December 4, 2063 at 03:43 AM UTC | December 31, 2063 at 11:33 AM UTC | 27.33 |
| 2815 | December 31, 2063 at 11:33 AM UTC | January 27, 2064 at 07:40 PM UTC | 27.34 |
| 2816 | January 27, 2064 at 07:40 PM UTC | February 24, 2064 at 03:49 AM UTC | 27.34 |
| 2817 | February 24, 2064 at 03:49 AM UTC | March 22, 2064 at 11:31 AM UTC | 27.32 |
| 2818 | March 22, 2064 at 11:31 AM UTC | April 18, 2064 at 06:18 PM UTC | 27.28 |
| 2819 | April 18, 2064 at 06:18 PM UTC | May 16, 2064 at 12:01 AM UTC | 27.24 |
| 2820 | May 16, 2064 at 12:01 AM UTC | June 12, 2064 at 04:58 AM UTC | 27.21 |
| 2821 | June 12, 2064 at 04:58 AM UTC | July 9, 2064 at 09:42 AM UTC | 27.20 |
| 2822 | July 9, 2064 at 09:42 AM UTC | August 5, 2064 at 02:47 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.