Two of these things are not like the others. Space offers plenty of mysteries for astronomers to solve, and there's one in our own Solar System that's been unexplained for decades: why are Venus and Uranus spinning in different directions to the other planets around the Sun? Venus spins on its axis from east to west, while Uranus is tilted so far over, it's virtually spinning on its side. Every other planet, including our own, spins from west to east, and scientists haven't figured out why. The planets should really all be spinning the same way: our Solar System was formed by a collapsing and rotating cloud of gas, and it's thought that the spin direction of most planets (like Earth) has been carried over from that ancient rotation. But Venus and Uranus are the exceptions: they have what's known as retrograde rotation, spinning counter to the rotation of the Sun. But how is this possible? One of the most long-standing hypotheses is that Venus and Uranus originally rotated counter