A recent study led by UK astronomers has challenged our longstanding perceptions of the colours of Neptune and Uranus. Contrary to the widely accepted belief that Neptune is rich blue and Uranus is green, new findings suggest that both ice giant planets share similar shades of greenish blue.
The revelation stems from a reevaluation of images captured during a space mission in the 1980s, which originally portrayed Neptune as a vibrant blue and Uranus as green.
However, the research discovered that these initial images of Neptune had been enhanced to highlight details of the planet's atmosphere, thereby distorting its true colour.
In the recent study, scientists used data from the Hubble Space Telescope and the European Southern Observatory's Very Large Telescope to reveal the true colours of Neptune and Uranus. By examining continuous spectra of colours captured by these instruments, researchers found that both planets share a greenish-blue shade.
Interestingly, Neptune has a hint of additional blue due to a thinner haze layer. The study also noted that Uranus appears a bit greener when one of its poles faces the Sun during summer and winter, while it takes on a bluer tinge during spring and autumn when the Sun is over the equator.
The earlier confusion about the colours of the two planets occurred because Voyager 2, the only spacecraft to visit both planets, took pictures using separate colour filters. When these images were combined and enhanced to highlight details, the original colours got mixed up and were eventually lost over time.
Lead researcher Patrick Irwin of the University of Oxford 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," reported UPI. Professor Irwin and his team stated that their recent finding of the colours is considered "the most accurate representation yet".
Professor Catherine Heymans, Astronomer Royal for Scotland and a University of Edinburgh astrophysics professor, told BBC, "They did something that I think everyone on Instagram will have done at some time in their life, they tweaked the colours. They accentuated the blue just to reveal the features that you can see in Neptune's atmosphere, and that's why the image looks very blue, but in reality, Neptune is actually pretty similar to Uranus."
Dr Robert Massey, the deputy director of the Royal Astronomical Society (RAS), clarified that the practice of enhancing images is a standard procedure in astronomical research. "You would be foolish to look at an astronomy image and not think it was enhanced. They have to be, because that is how they are processed in order to see things. It's not that there was any conspiracy to keep it from the public!"
