Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 4074
| Start | January 7, 2158 at 12:13 AM UTC |
|---|---|
| End | February 3, 2158 at 08:22 AM UTC |
| Length (days) | 27.34 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 4069 | August 23, 2157 at 12:44 PM UTC | September 19, 2157 at 06:53 PM UTC | 27.26 |
| 4070 | September 19, 2157 at 06:53 PM UTC | October 17, 2157 at 01:38 AM UTC | 27.28 |
| 4071 | October 17, 2157 at 01:38 AM UTC | November 13, 2157 at 08:47 AM UTC | 27.30 |
| 4072 | November 13, 2157 at 08:47 AM UTC | December 10, 2157 at 04:19 PM UTC | 27.31 |
| 4073 | December 10, 2157 at 04:19 PM UTC | January 7, 2158 at 12:13 AM UTC | 27.33 |
| 4074 | January 7, 2158 at 12:13 AM UTC | February 3, 2158 at 08:22 AM UTC | 27.34 |
| 4075 | February 3, 2158 at 08:22 AM UTC | March 2, 2158 at 04:28 PM UTC | 27.34 |
| 4076 | March 2, 2158 at 04:28 PM UTC | March 30, 2158 at 12:01 AM UTC | 27.31 |
| 4077 | March 30, 2158 at 12:01 AM UTC | April 26, 2158 at 06:36 AM UTC | 27.27 |
| 4078 | April 26, 2158 at 06:36 AM UTC | May 23, 2158 at 12:09 PM UTC | 27.23 |
| 4079 | May 23, 2158 at 12:09 PM UTC | June 19, 2158 at 05:01 PM UTC | 27.20 |
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.