Regardless of its composition, the Sun is massive - meaning it has a lot of mass. As such, according to Einstein's model of the Universe described in general relativity, it deforms spacetime creating a gravitational "well". The result is that the planets hang around in this well around the Sun.
Gravity...
Regardless of its composition, the Sun is massive - meaning it has a lot of mass. As such, according to Einstein's model of the Universe described in general relativity, it deforms spacetime creating a gravitational "well". The result is that the planets hang around in this well around the Sun.