What causes the Earth rotate on its axis?
The earth spins on its axis because of the way that it was formed. The entire solar system was formed at about the same time as the sun, 4.6 billion years ago. Before that time there was just a large cloud of gas and dust. The cloud eventually began to collapse on itself, which was the beginning of the formation of the sun. It didn’t, however, collapse straight in on itself, it began to swirl in, like when you let water go down the drain. This swirling motion created some eddies, as also happens on occasion when the water goes down the drain. These other smaller swirls began to clump matter together too, and that is what made the planets. Since it was a spinning motion that formed the earth, it is natural that it just kept spinning afterward.
