Star of Milky Way
Sun
The star that sets every planet, moon, and comet in motion.
The Sun anchors the solar system, and its gravity steers every planet, moon, and comet on its path. It is not solid, so it spins faster at the equator (about 25 days) than at the poles (about 36 days). The Sun itself is on the move too, carrying the whole solar system around the center of the Milky Way.
How it moves
- At its equator the Sun rotates once in about 25 Earth days, while near the poles one turn takes about 36 days.
- The adopted sidereal rotation period, measured at 16 degrees latitude, is 609.12 hours (about 25.4 days).
- The Sun's spin axis is tilted 7.25 degrees from the plane of the planets' orbits.
- The solar system travels around the Milky Way at about 720,000 km/h and needs about 230 million years for one lap.
- Roughly every 11 years the Sun's magnetic poles swap places, marking one solar cycle.
Facts
- Mean radius
- 695,700 km
- Mass
- 1.988e+30 kg
- Surface gravity
- 274 m/s²
- Rotation period
- 609.12 hours
- Axial tilt
- 7.25°
- Discovered
- Known since antiquity
The Sun holds about 99.8% of all the mass in the solar system.
Sources: nssdc.gsfc.nasa.gov, science.nasa.gov