Figure 11.6 Exaggerated seasons on Uranus.

forms higher clouds over Uranus. Methane absorbs red light, giving Uranus its blue-green colour.

In the interior, the temperature rises rapidly to about 2300°C in the mantle and about 7000°C in the rocky core. The pressure in the core is about 20 million times that of the atmosphere at Earth's surface.

The planet radiates back into space as much heat as it receives from the Sun. Because its axis is tilted at 98°, its poles receive more sunlight during a Uranian year than does its equator. However, the weather system seems to distribute heat fairly evenly over the planet.

As the planet orbits the Sun, its north and south poles alternately point directly towards or directly away from the Sun, resulting in exaggerated seasons. During summer near the north pole, the Sun is almost directly overhead for many Earth years. At the same time southern latitudes are subjected to a continuous frigid winter night. Forty-two years later, the situation is reversed.

In August 2006, the Hubble Space Telescope captured images of a huge dark cloud on Uranus. The cloud measured about 1700 km by 3000 km. Scientists are not certain about the origin of the cloud; nor do they now how long it will last.

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