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The Sun's motion around the barycenter approximately repeats every 179 years, rotated by about 30° due primarily to the synodic period of Jupiter and Saturn. [152] The Sun's gravitational field is estimated to dominate the gravitational forces of surrounding stars out to about two light-years (125,000 AU).
Thus, the Sun occupies 0.00001% (1 part in 10 7) of the volume of a sphere with a radius the size of Earth's orbit, whereas Earth's volume is roughly 1 millionth (10 −6) that of the Sun. Jupiter, the largest planet, is 5.2 AU from the Sun and has a radius of 71,000 km (0.00047 AU; 44,000 mi), whereas the most distant planet, Neptune, is 30 AU ...
It is almost perfectly spherical and consists of hot plasma and magnetic fields. [ 3 ] [ 4 ] It has a diameter of about 1,392,684 kilometres (865,374 mi), [ 5 ] around 109 times that of Earth , and its mass (1.989 × 10 30 kilograms, approximately 330,000 times that of Earth) accounts for some 99.86% of the total mass of the Solar System. [ 6 ]
This apsidal precession is observed for all the planets orbiting the Sun, primarily due to the oblateness of the Sun (it is not perfectly spherical) and the attractions of the other planets to one another. The apsides are the two points of closest and furthest distance of the orbit (the periapsis and apoapsis, respectively); apsidal precession ...
This represents the power per unit area of solar irradiance across the spherical surface surrounding the Sun with a radius equal to the distance to the Earth (1 AU). This means that the approximately circular disc of the Earth, as viewed from the Sun, receives a roughly stable 1361 W/m 2 at all times.
The Sun has a radiative core and a convective outer envelope. In the core, the luminosity due to nuclear reactions is transmitted to outer layers principally by radiation. However, in the outer layers the temperature gradient is so great that radiation cannot transport enough energy.
Solar System objects more massive than 10 21 kilograms are known or expected to be approximately spherical. Astronomical bodies relax into rounded shapes ( spheroids ), achieving hydrostatic equilibrium , when their own gravity is sufficient to overcome the structural strength of their material.
The core of the Sun is considered to extend from the center to about 0.2 of the solar radius (139,000 km; 86,000 mi). [1] It is the hottest part of the Sun and of the Solar System . It has a density of 150,000 kg/m 3 (150 g/cm 3 ) at the center, and a temperature of 15 million kelvins (15 million degrees Celsius; 27 million degrees Fahrenheit).