Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 487
| Start | February 24, 1890 at 09:04 PM UTC |
|---|---|
| End | March 24, 1890 at 04:39 AM UTC |
| Length (days) | 27.32 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 482 | October 11, 1889 at 06:16 AM UTC | November 7, 1889 at 01:24 PM UTC | 27.30 |
| 483 | November 7, 1889 at 01:24 PM UTC | December 4, 1889 at 08:55 PM UTC | 27.31 |
| 484 | December 4, 1889 at 08:55 PM UTC | January 1, 1890 at 04:48 AM UTC | 27.33 |
| 485 | January 1, 1890 at 04:48 AM UTC | January 28, 1890 at 12:57 PM UTC | 27.34 |
| 486 | January 28, 1890 at 12:57 PM UTC | February 24, 1890 at 09:04 PM UTC | 27.34 |
| 487 | February 24, 1890 at 09:04 PM UTC | March 24, 1890 at 04:39 AM UTC | 27.32 |
| 488 | March 24, 1890 at 04:39 AM UTC | April 20, 1890 at 11:17 AM UTC | 27.28 |
| 489 | April 20, 1890 at 11:17 AM UTC | May 17, 1890 at 04:52 PM UTC | 27.23 |
| 490 | May 17, 1890 at 04:52 PM UTC | June 13, 1890 at 09:45 PM UTC | 27.20 |
| 491 | June 13, 1890 at 09:45 PM UTC | July 11, 1890 at 02:30 AM UTC | 27.20 |
| 492 | July 11, 1890 at 02:30 AM UTC | August 7, 1890 at 07:40 AM UTC | 27.22 |
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.