Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 1517
| Start | January 26, 1967 at 07:02 AM UTC |
|---|---|
| End | February 22, 1967 at 03:11 PM UTC |
| Length (days) | 27.34 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 1512 | September 11, 1966 at 05:54 PM UTC | October 9, 1966 at 12:33 AM UTC | 27.28 |
| 1513 | October 9, 1966 at 12:33 AM UTC | November 5, 1966 at 07:38 AM UTC | 27.30 |
| 1514 | November 5, 1966 at 07:38 AM UTC | December 2, 1966 at 03:05 PM UTC | 27.31 |
| 1515 | December 2, 1966 at 03:05 PM UTC | December 29, 1966 at 10:54 PM UTC | 27.33 |
| 1516 | December 29, 1966 at 10:54 PM UTC | January 26, 1967 at 07:02 AM UTC | 27.34 |
| 1517 | January 26, 1967 at 07:02 AM UTC | February 22, 1967 at 03:11 PM UTC | 27.34 |
| 1518 | February 22, 1967 at 03:11 PM UTC | March 21, 1967 at 10:53 PM UTC | 27.32 |
| 1519 | March 21, 1967 at 10:53 PM UTC | April 18, 1967 at 05:41 AM UTC | 27.28 |
| 1520 | April 18, 1967 at 05:41 AM UTC | May 15, 1967 at 11:25 AM UTC | 27.24 |
| 1521 | May 15, 1967 at 11:25 AM UTC | June 11, 1967 at 04:22 PM UTC | 27.21 |
| 1522 | June 11, 1967 at 04:22 PM UTC | July 8, 1967 at 09:06 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.