Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 2946
| Start | October 12, 2073 at 10:20 AM UTC |
|---|---|
| End | November 8, 2073 at 05:28 PM UTC |
| Length (days) | 27.30 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 2941 | May 29, 2073 at 06:34 AM UTC | June 25, 2073 at 11:20 AM UTC | 27.20 |
| 2942 | June 25, 2073 at 11:20 AM UTC | July 22, 2073 at 04:11 PM UTC | 27.20 |
| 2943 | July 22, 2073 at 04:11 PM UTC | August 18, 2073 at 09:34 PM UTC | 27.22 |
| 2944 | August 18, 2073 at 09:34 PM UTC | September 15, 2073 at 03:39 AM UTC | 27.25 |
| 2945 | September 15, 2073 at 03:39 AM UTC | October 12, 2073 at 10:20 AM UTC | 27.28 |
| 2946 | October 12, 2073 at 10:20 AM UTC | November 8, 2073 at 05:28 PM UTC | 27.30 |
| 2947 | November 8, 2073 at 05:28 PM UTC | December 6, 2073 at 12:57 AM UTC | 27.31 |
| 2948 | December 6, 2073 at 12:57 AM UTC | January 2, 2074 at 08:48 AM UTC | 27.33 |
| 2949 | January 2, 2074 at 08:48 AM UTC | January 29, 2074 at 04:57 PM UTC | 27.34 |
| 2950 | January 29, 2074 at 04:57 PM UTC | February 26, 2074 at 01:05 AM UTC | 27.34 |
| 2951 | February 26, 2074 at 01:05 AM UTC | March 25, 2074 at 08:43 AM UTC | 27.32 |
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.