A unit of length, representing the radius of the Sun, used to express the size of stars in astrophysics. It is equivalent to: 695,700 km, 0.00465047 astronomical units, 7.35355 x 10^-8 light-years, an
d 2.32061 light-seconds.
The motion of the Sun around an axis which is roughly perpendicular to the plane of the ecliptic; the Sun's rotational axis is tilted by 7.25° from perpendicular to the ecliptic. It rotates in the cou
nterclockwise direction (when viewed from the north), the same direction that the planets rotate (and orbit around the Sun). The Sun's rotation is differential, i.e. the period varies with latitude on the Sun (differential rotation). Equatorial regions rotate in about 25.6 days. The regions at 60 degrees latitude rotate more slowly, in about 30.9 days.
(1) synodic: 13.39 degrees -2.7 degrees sin2 J per day (J = solar latitude). (2) sidereal: 14.38 degrees -2. 7 degrees sin2 J per day. The difference between sidereal and synodic rates is the Earth or
bital motion of 0.985 degrees/day.
The boundary between large-scale unipolar magnetic regions on the Sun’s surface, as determined from inversion lines mapped using filaments and filament channels, or large-scale magnetograms. The suppo
sed solar signature of an interplanetary sector boundary.
The visible surface of the Sun or some other star; it lies just below the Chromosphere and just above the Convective Zone and has a temperature of about 6,000 K
The collective name for the Sun and all objects gravitationally bound to it. These objects are the eight planets, their 166 known moons, five dwarf planets, and billions of small bodies. The small bod
ies include asteroids, icy Kuiper belt objects, comets, meteoroids, and interplanetary dust. The solar system is roughly a sphere with a radius greater than 100,000 AU. Planets, satellites, and all interplanetary material together comprise only about 1/750 of the total mass. Geochemical dating methods show that the solar system chemically isolated itself from the rest of the Galaxy (4.7 ± 0.1) x 10^9 years ago.