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Solar Rotation Applet

 

You may use the keys "m", "d", "h", "n" to increase the month, date, hour, or minute,
or
shift key and "m", "d", "h", "n" to decrease the month, date, hour, or minute.
Click the applet first !

latitude
                  longitude horizon view
Select latitude: northern positive, southern negative,
select longitude: eastern positive, western negative.
The regions of the Sun near its equator rotate once every 25 days. The Sun's rotation rate decreases with increasing latitude, so that its rotation rate is slowest near its poles. At its poles the Sun rotates once every 36 days!
The regions of the Sun near its equator rotate once every 25 days (synodic period). The Sun's rotation rate decreases with increasing latitude, so that its rotation rate is slowest near its poles. At its poles the Sun rotates once every 36 days (synodic period).

sidereal
                      period of solar rotation


The Sun rotates on its axis once in about 27 days. This rotation was first detected by observing the motion of sunspots (animation). The Sun's rotation axis is tilted by about 7.25° from the axis of the Earth's orbit.

N, S = poles of the ecliptic

SNP = Solar North Pole

Solar coordinates
(from:
Glossary of Solar-Terrestrial Terms)

P = The position angle between the geocentric north pole and the solar rotational north pole measured eastward from geocentric north. The range in P is +/- 26.3°.

B0= Heliographic latitude of the central point of the solar disk.

The range of B0 is +/- 7.23°, correcting for the tilt of the ecliptic with respect to the solar equatorial plane.

L0= Heliographic longitude of the central point of the solar disk.

The longitude value is determined with reference to a system of fixed longitudes rotating on the sun at a rate of 13.2 °/day (the mean rate of rotation observed from central meridian transits of sunspots). The standard meridian on the sun is defined to be the meridian that passed through the ascending node of the sun's equator on 1 January 1854 at 1200 UTC and is calculated for the present day by assuming a uniform sidereal period of rotation of 25.38 days (synodic rotation period of 27.2753 days, Carrington rotation).

The applet is using the algorithm from Meeus, Jean: Astronomical Algorithms

B0, the heliographic latitude of the central point of the solar disk, in 2006


P, the position angle, in 2006


B0 and P in 2006


B0
P
Minimum
-7.250°
Mar 06
-26.283°
Apr 06
Maximum
7.250°
Sep 08
26.283°
Oct 10
Zero
Jun 06
Dec 08
Jan 05
Jul 07

Extreme values of B0 and P in 2006

heliographic longitude latitude

Heliographic latitude B0 vs. longitude L0 in 2007

2007 Solar ephemerids and parameters (Carrington rotation, B0, L0, P)

apparent diameter of the Sun

Date
Distance/AU
Diameter/'
Jan 2 to 5
Perihelion

0.983260
32.53
+1.7 %
~Oct 5, ~Apr 3
Mean
1 31.98
+/- 0 %
Jul 3 to 7
Aphelion
1.01671 31.45
-1.7 %


Perihelion and Aphelion Sun Comparison


Applet: Limb Darkening of the Sun

Web Links

Solar Rotation (Wikipedia)

The inclination of the Sun's rotation axis

Definitions of solar coordinates

Glossary of Solar-Terrestrial Terms

Ephemerids, Grids, Date conversion

Maps of Active Solar Regions

Solar Coordinates of Observed Sun Spots

Base de données Solaire Sol 2000, archive of french ground-based solar data
(
Solar ephemerids and parameters (Carrington rotation, B0, L0, P)

Calculation of solar parameters: P, B0, L0, Carrington Rotation number,...

Solar rotation showing passage of sunspots (ESA)


Updated: 2012, Jan 10