Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 1529
| Start | December 19, 1967 at 12:15 PM UTC |
|---|---|
| End | January 15, 1968 at 08:17 PM UTC |
| Length (days) | 27.33 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 1524 | August 5, 1967 at 02:11 AM UTC | September 1, 1967 at 07:56 AM UTC | 27.24 |
| 1525 | September 1, 1967 at 07:56 AM UTC | September 28, 1967 at 02:21 PM UTC | 27.27 |
| 1526 | September 28, 1967 at 02:21 PM UTC | October 25, 1967 at 09:16 PM UTC | 27.29 |
| 1527 | October 25, 1967 at 09:16 PM UTC | November 22, 1967 at 04:35 AM UTC | 27.30 |
| 1528 | November 22, 1967 at 04:35 AM UTC | December 19, 1967 at 12:15 PM UTC | 27.32 |
| 1529 | December 19, 1967 at 12:15 PM UTC | January 15, 1968 at 08:17 PM UTC | 27.33 |
| 1530 | January 15, 1968 at 08:17 PM UTC | February 12, 1968 at 04:29 AM UTC | 27.34 |
| 1531 | February 12, 1968 at 04:29 AM UTC | March 10, 1968 at 12:25 PM UTC | 27.33 |
| 1532 | March 10, 1968 at 12:25 PM UTC | April 6, 1968 at 07:36 PM UTC | 27.30 |
| 1533 | April 6, 1968 at 07:36 PM UTC | May 4, 1968 at 01:45 AM UTC | 27.26 |
| 1534 | May 4, 1968 at 01:45 AM UTC | May 31, 1968 at 06:57 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.