to extend into the solar interior as rotating cylinders of constant angular momentum. Through helioseismology this is now known not to be the case and the rotation profile of the Sun has been found. On the surface, the Sun rotates slowly at the poles and quickly at the equator. This profile extends on roughly radial lines through the solar convection zone to the interior. At the tachocline the rotation abruptly changes to solid-body rotation in the solar radiation zone. See also Differential rotation in stars Magnetohydrodynamics Orbital period Tachocline References Cox, Arthur N., Ed. "Allen's Astrophysical Quantities", 4th Ed, Springer, 1999. Javaraiah, J., 2003. Long-Term Variations in the Solar Differential Rotation. Solar Phys., 212 (1): 23-49. St. John, C., 1918. The present condition of the problem of solar rotation, Publications of the Astronomical Society of the Pacific, V.30, No. 178, 319-325. External links Carrington Rotation Commencement Dates 1853-2016 Carrington Rotation Start and Stop Times Carrington Rotation Number Sun Articles containing video clips