The Sun is an ordinary yellow dwarf star, fusing hydrogen into helium in its core, and the source of almost all the light and heat in the Solar System.
At a glance
| type | yellow star (class G) |
|---|---|
| surface temperature | 5,772 K |
| light to Earth | 8.32 minutes |
| radius | 696,000 km |
Read off the piece’s own catalogue, the same values it draws with.
About The Sun
The Sun is a ball of hot, ionised gas, mostly hydrogen and helium, held together by its own gravity. In its core the pressure and temperature are high enough for hydrogen nuclei to fuse into helium, and the energy released works its way slowly outward before leaving the surface as sunlight. It holds nearly all the mass of the Solar System; every planet, moon and comet together is a rounding error beside it.
We know what happens in the core without seeing it. Neutrinos made by the fusion reactions pass straight out through the Sun and are caught in detectors deep underground on Earth, and the way the whole surface rings with sound waves, studied as helioseismology, maps the interior layer by layer. On the surface, dark sunspots come and go in a regular cycle driven by the tangled magnetic field, which also powers flares and the solar wind.
Among the stars of the Milky Way the Sun is unremarkable: brighter than most of its neighbours, which are faint red dwarfs, but far outshone by the hot blue stars of the spiral arms. It sits in the Orion Spur, between two major arms, and carries its planets round the centre of the Galaxy in a slow orbit.
What you see in the piece
Close in, the Sun is a white disc tinged faintly yellow, the colour of its surface temperature. Fly away from it and it shrinks to a point and fades like any other star, falling below what the eye can see long before you reach the edge of the Local Bubble.
Questions
How long does sunlight take to reach Earth?
Light from the Sun takes 8.32 minutes to reach Earth, so you always see the Sun as it was 8.32 minutes earlier, never as it is now.
What type of star is the Sun?
The Sun is a yellow star (class G), a main-sequence star steadily fusing hydrogen into helium in its core, with a surface temperature of 5,772 K.