Stars are giant balls of burning gas, really far away. The nearest star is the sun, but its still 148.78 million kilometers away. It would take over 3700 years to walk to the sun. There are seven main types of stars: O, B, A, F, G, K and M. The O stars are blue, B stars are blue-white, A stars are white, F stars are yellow-white, G stars are yellow, K stars are orange, and M stars are red.