# Why do Uranus and Venus rotate from East to west?

Why do only Uranus and Venus rotate from East to west, while others rotate in opposite direction? Is it because of the angle of their tiltness? Or due to the process of their formation?

• The planets did not form this way, something happened to them later. What do you wish to know beyond that which is clearly addressed by many popular resources such as Wikipedia? – Rob Jeffries Aug 22 '15 at 8:56
• possible duplicate (or related at least): physics.stackexchange.com/q/25153 – user81619 Aug 22 '15 at 8:56
• Possible duplicates: physics.stackexchange.com/q/7819/2451 and links therein. – Qmechanic Aug 24 '15 at 16:10

Venus has an axial tilt of 177$^\circ$, so it rotates backwards compared to the majority of other planets. It also has an extremely slow rotation rate of one rotation every 244 days. In comparison, Uranus rotates every 17 hours, but has an axial tilt of 98$^\circ$. It rotates in a direction almost in the same plane as its orbital motion.
Unfortunately, it's very hard to work out the details. This is because on the scale of billions of years, the evolution of the solar system is chaotic, with tiny changes in initial inclinations or positions leading to radically different results after billions of years. As an example, take a look at this figure from `Long term evolution of the spin of Venus - II. Numerical simulations', A.C.M. Correia et al, showing the evolution of the Venus spin over time. It's pretty wacky, especially near 30$^\circ$.