Carrington rotation
Encyclopedia
The Carrington rotation of the Sun
is a system for comparing locations on the Sun over a period of time, allowing the following of sunspot
groups or reappearance of eruptions at a later time.
Because the Solar rotation is variable with latitude, depth and time, any such system is necessarily arbitrary and only makes comparison meaningful over moderate periods of time. Differential rotation
is when different latitudes rotate at different rates and applies to all fluid bodies including all stars and the surface of gas giant planets. Solar rotation
is arbitrarily taken to be 27.2753 days for the purpose of Carrington rotations. Each rotation of the Sun under this scheme is given a unique number called the Carrington Rotation Number, starting from November 9, 1853. (The Bartels Rotation Number is a similar numbering scheme that uses a period of exactly 27 days and starts from February 8, 1832.)
Richard Christopher Carrington
determined the solar rotation rate from low latitude sunspots in the 1850s and arrived at 25.38 days for the sidereal rotation period. Sidereal rotation is measured relative to the stars, but because the Earth is orbiting the Sun, we see this period as 27.2753 days.
It is possible to construct a diagram with the longitude of sunspots horizontally and time vertically. The longitude is measured by the time of crossing the central meridian and based on the Carrington rotations. In each rotation, plotted under the preceding ones, most sunspots or other phenomena will reappear directly below the same phenomenon on the previous rotation. There may be slight drifts left or right over longer periods of time.
The Condegram spiral plot
is another technique for expressing the approximate 27 day periodicity of various phenomena originating at the solar surface.
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
is a system for comparing locations on the Sun over a period of time, allowing the following of sunspot
Sunspot
Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature....
groups or reappearance of eruptions at a later time.
Because the Solar rotation is variable with latitude, depth and time, any such system is necessarily arbitrary and only makes comparison meaningful over moderate periods of time. Differential rotation
Differential rotation
Differential rotation is seen when different parts of a rotating object move with different angular velocities at different latitudes and/or depths of the body and/or in time. This indicates that the object is not solid. In fluid objects, such as accretion disks, this leads to shearing...
is when different latitudes rotate at different rates and applies to all fluid bodies including all stars and the surface of gas giant planets. Solar rotation
Solar rotation
Solar rotation is able to vary with latitude because the Sun is composed of a gaseous plasma. The rate of rotation is observed to be fastest at the equator , and to decrease as latitude increases...
is arbitrarily taken to be 27.2753 days for the purpose of Carrington rotations. Each rotation of the Sun under this scheme is given a unique number called the Carrington Rotation Number, starting from November 9, 1853. (The Bartels Rotation Number is a similar numbering scheme that uses a period of exactly 27 days and starts from February 8, 1832.)
Richard Christopher Carrington
Richard Christopher Carrington
Richard Christopher Carrington was an English amateur astronomer whose 1859 astronomical observations demonstrated the existence of solar flares as well as suggesting their electrical influence upon the Earth and its aurorae; and whose 1863 records of sunspot observations revealed the differential...
determined the solar rotation rate from low latitude sunspots in the 1850s and arrived at 25.38 days for the sidereal rotation period. Sidereal rotation is measured relative to the stars, but because the Earth is orbiting the Sun, we see this period as 27.2753 days.
It is possible to construct a diagram with the longitude of sunspots horizontally and time vertically. The longitude is measured by the time of crossing the central meridian and based on the Carrington rotations. In each rotation, plotted under the preceding ones, most sunspots or other phenomena will reappear directly below the same phenomenon on the previous rotation. There may be slight drifts left or right over longer periods of time.
The Condegram spiral plot
Condegram spiral plot
The Condegram spiral plot is an illustrative device developed by , Associate Professor at the University of Alaska, Fairbanks to display space weather data. Space weather effects on Earth are ultimately driven by processes originating with the Sun, many of which are communicated to Earth by the...
is another technique for expressing the approximate 27 day periodicity of various phenomena originating at the solar surface.