According to the Big Bang, the whole universe started out as a tiny spinning object. This object would have been in a frictionless environment. The Conservation of Angular Momentum tells us that in a frictionless environment, if pieces fly off a spinning object they tend to spin in the same direction. This is due to the fact that the outer part is spinning faster than the inner part. If this whole universe began from the big bang, everything should be spinning the same way. However, everything is not spinning in the same direction. Two of the planets, Venus and Uranus, rotate backwards. Six of the moons in the solar system also rotate backwards...that pretty tough on the big bang theory