[grey_whiskers]

Weighing as much or more than the sun but only as big as asteroids, they can rotate tens or even hundreds of times a second (versus once a day for Earth).

IF the sun rotates, is it "exactly" in phase with the Earth? And does the sun's axis of rotation coincide with the axis of the Earth's orbit?

Cheers!

[JasonC]

The sun rotates, slower than the earth it degrees a day but then it is much larger. The axis of its roration is nearly perpendicular to the plane of the orbits of the major planets, but is "off" by about 7 degrees from perfectly vertical. The speed of the rotation varies with the latitude, being fastest at the equator and slower at the poles. (Remember the sun surface is gas, like an atmosphere, not solid). The rotational period is about 25 days at the equator and about 36 days at the poles.

[ngc6656]

IF the sun rotates, is it "exactly" in phase with the Earth? And does the sun's axis of rotation coincide with the axis of the Earth's orbit?

The answer to both questions is no.

The Sun's sidereal period of rotation is 25.35 days; its synodic period -- the time for it to make a full rovolution plus the additional time required for it to "catch up" to compensate for Earth's rotation along its orbit around the Sun -- is 27.25 days.

The plane of Earth's orbit around the Sun, known as the "ecliptic," is the fundamental plane of reference in our solar system. On star maps it is shown as a line that marks the Sun's apparent path against the background of the stars during the course of a year. Earth's axis of rotation is inclined 23.75 degrees off a perpendicular to the ecliptic; the Sun's rotational axis is inclined 7.25 degrees off a perpendicular to the ecliptic.