What keeps earth from falling in to the sun ?

The Earth is always being pulled towards the Sun by gravity. The Earth is not moving fast enough to "escape" the Sun's gravity and leave the solar system, but it is going too fast to be pulled into the Sun. Therefore, it keeps going around and around - orbiting the Sun

Your answer is pretty much "Gravity"

a sonic boom is a loud boom that breaks the sound barrier

explanation:

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.