It has gravity because it has mass,it has nothing to do with the fact that it is so much bigger than the earth. If you could shrink the sun down to the size of a basketball it would still have the same mass. A black hole the size of the earth could have more gravity than the sun, because of more mass.it could eat the whole sun.
10 months ago
Last edited at 10:08AM on 6/10/2013
The Sun has gravity because it contains matter. It therefore has mass. The Earth is massive enough (contains enough matter) that its gravity holds us to it. It is Earth's gravity that makes us all weigh something. The amount we weigh depends on our own mass (the more matter I am made of, the stronger the affect of Earth's gravity on me). You can test this yourself by jumping. Hopefully you won't float into space!
The same rules apply to the Sun. It's a lot more massive than Earth (330,000 times more). Because of this, and taking into account that its volume is 1,300,000 that of earth and that it's made of the 'light' elements Helium and Hydrogen, its gravity is about 28 times that of Earth. So, in the same way as Earth's gravity can hold the moon in orbit, the Sun's gravity holds Earth, and all other matter in the solar system.
Why does matter have gravity? I doubt the greatest physicists could answer that question fully and clearly. The best I can do is this - Matter itself bends space-time (the dimensions of the universe), and the other objects in the universe 'fall' into the dips and troughs created in the fabric of the universe by the most massive of objects.