Carrington rotations
Convert a date to its Carrington rotation number and back, and browse rotation start and end times.
CR 2016
| Start | May 1, 2004 at 05:43 PM UTC |
|---|---|
| End | May 28, 2004 at 11:00 PM UTC |
| Length (days) | 27.22 |
Neighbouring rotations
| CR | Start | End | Length (days) |
|---|---|---|---|
| 2011 | December 17, 2003 at 04:01 AM UTC | January 13, 2004 at 12:01 PM UTC | 27.33 |
| 2012 | January 13, 2004 at 12:01 PM UTC | February 9, 2004 at 08:12 PM UTC | 27.34 |
| 2013 | February 9, 2004 at 08:12 PM UTC | March 8, 2004 at 04:11 AM UTC | 27.33 |
| 2014 | March 8, 2004 at 04:11 AM UTC | April 4, 2004 at 11:28 AM UTC | 27.30 |
| 2015 | April 4, 2004 at 11:28 AM UTC | May 1, 2004 at 05:43 PM UTC | 27.26 |
| 2016 | May 1, 2004 at 05:43 PM UTC | May 28, 2004 at 11:00 PM UTC | 27.22 |
| 2017 | May 28, 2004 at 11:00 PM UTC | June 25, 2004 at 03:45 AM UTC | 27.20 |
| 2018 | June 25, 2004 at 03:45 AM UTC | July 22, 2004 at 08:36 AM UTC | 27.20 |
| 2019 | July 22, 2004 at 08:36 AM UTC | August 18, 2004 at 02:01 PM UTC | 27.23 |
| 2020 | August 18, 2004 at 02:01 PM UTC | September 14, 2004 at 08:07 PM UTC | 27.25 |
| 2021 | September 14, 2004 at 08:07 PM UTC | October 12, 2004 at 02:49 AM UTC | 27.28 |
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.