Sunlight holds the key to planet’s shine

Scientists have discovered how the sun's influence on the remote planet Uranus changes its brightness in the sky. Changes in solar activity influence the colour and formation of clouds around the planet, researchers at Oxford and Reading universities found. The icy planet is second furthest from the sun in the solar system and takes 84 Earth years to complete a full orbit - one Uranian year. The researchers found that, once the planet's long and strange seasons are taken into account, it appears brighter and dimmer over a cycle of 11 years. This is the regular cycle of solar activity which also affects sun spots. Karen Aplin of Oxford University's Department of Physics carried out the research with Giles Harrison, an atmospheric physicist from the Department of Meteorology at the University of Reading. Dr Aplin said: 'The atmosphere around Uranus is one of the coldest in the solar system, but still contains clouds and ice, like our own atmosphere here on Earth.