Guest essay by David Archibald
“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.
“The changing brightness of the planet shows that something is happening to the clouds. We have found that the change is caused by two processes.
“One is chemical, caused as fluctuating levels of UV sunlight alters the colour of particles in the atmosphere. The other is due to high-speed particles from outside the solar system, known as galactic cosmic rays, bombarding the atmosphere and influencing the formation of clouds.”
The scientists used data from telescopes on Earth, as well as cosmic rays measured by the Voyager 2 spacecraft, to make their assessment.
To put that solar effect into perspective…
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