We’ve got some news we need to share with you about Uranus.
Scientists have been studying it hard and discovered that things aren’t what we always believed.
It turns out Uranus is a different colour to what we previously thought.
Uranus is also significantly affected by gas – notably methane. And all that means Uranus really is subject to seasonal variations.
Oxford University Professor Patrick Irwin and his team have been studying Uranus in great detail. He’s produced some of the best quality images ever seen of Uranus and it’s got scientists excited.
For years we’ve been looking at old pictures of Uranus taken by the Voyager probe, but it turns out they didn’t do it justice.
Talking about what he found on Uranus (and Neptune), Professor Irwin said: ‘Although the familiar Voyager 2 images of Uranus were published in a form closer to “true” colour, those of Neptune were, in fact, stretched and enhanced, and therefore made artificially too blue.
‘Even though the artificially-saturated colour was known at the time amongst planetary scientists – and the images were released with captions explaining it – that distinction had become lost over time.
‘Applying our model to the original data, we have been able to reconstitute the most accurate representation yet of the colour of both Neptune and Uranus.’
Early images of Neptune from Voyager 2 were also strongly contrast enhanced to better reveal the clouds, bands, and winds that shape what we have come to think the planet looks like, scientists say.
The Oxford team used new data from the Hubble Space Telescope and the European Southern Observatory’s Very Large Telescope to re-balance the composite colour images sent back from deep space to create more accurate images of the solar system’s two most distant planets.
The findings also answered another question about Uranus that has been perplexing scientists for decades – why it changes colour during its 84-year journey around the Sun.
It’s all about methane.
It turns out the colour changes depending on how much methane is at the planet’s poles. Unlike all the other planets, Uranus spins on its side, meaning the north pole is facing the Sun for half the year, and the south pole the other half.
Scientists think this happened because, billions of years ago, something huge and hard smashed into Uranus and made a huge mess, knocking it over.
At certain times of year the layer of methane ice crystals grows thicker, which absorbs red light, making it appear more green.
‘This is the first study to match a quantitative model to imaging data to explain why the colour of Uranus changes during its orbit,’ said Professor Irwin.
‘In this way, we have demonstrated that Uranus is greener at the solstice due to the polar regions having reduced methane abundance but also an increased thickness of brightly scattering methane ice particles.’
So there you have it. Uranus is green-blue – but greener when there’s an abundance of methane.
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