Our Sun is a normal main-sequence G2 star, one of more than 100
billion stars in our galaxy. diameter: 1,390,000 km. mass:
1.989e30 kg temperature: 5800 K (surface) 15,600,000 K (core)
The Sun is by far the largest object in the solar system. It
contains more than 99.8% of the total mass of the Solar System
(Jupiter contains most of the rest). It is often said that the
Sun is an "ordinary" star. That's true in the sense that there
are many others similar to it. But there are many more smaller
stars than larger ones; the Sun is in the top 10% by mass. The
median size of stars in our galaxy is probably less than half
the mass of the Sun. The Sun is personified in many mythologies:
the Greeks called it Helios and the Romans called it Sol. The
Sun is, at present, about 70% hydrogen and 28% helium by mass
everything else ("metals") amounts to less than 2%. This changes
slowly over time as the Sun converts hydrogen to helium in its
core. The outer layers of the Sun exhibit differential rotation:
at the equator the