Uranus' axis is almost inline with the ecliptic (the plane of the planets revolution around the Sun). Uranus still has seasons: the south summer lasts for 1/4 of the orbit, about 21 years. Then gradually, for the next 21 years, the Sun would appear over the equator, passing through equinox. Next, the north pole of Uranus would be fully illuminated for about 21 years, and so on. At the time of Voyager 2's passage, Uranus' south pole was pointed almost directly at the Sun.

How did the rotational axis of Uranus get tilted?
When something strange is found in the Solar System, the scientists like to suggest the "collision theory".. And this is indeed what may have happened to Uranus: It is known from the cratering evidence we see on a variety of planetary surfaces, that soon after the planets were formed, there were still some mighty large mini-planets orbiting the Sun. One of these may have collided with the Earth, dredging up material that later solidified into our Moon. The material from the Uranus collision didn't form a separate moon, but was absorbed into Uranus. In addition to mass and kinetic energy, the collision would also have contributed angular momentum. The result is that the spin direction and speed for Uranus could have been seriously altered from its initial state. This theory has also been suggested to explain why Venus rotates backwards.

The composition of Uranus
The Uranus atmosphere is composed of about 83 percent hydrogen, 15 percent helium, 2 percent methane, and tiny amounts of ethane and other gases. The methane gives Uranus is blue-green color, as this molecule absorbs red light more efficiently than blue. Very faint bands do exist within the clouds parallel to the equator, as well as "hurricane" spots (like Jupiter and Saturn), but are only seen in high contrast computer images. Uranus appears to have a core, or center, of melted rock, which changes into a dirty ocean made of water, ammonia and other elements further from the center. The planet layers are not separate but gradually blend with one another.