Our perceptions of the colors of the planets Neptune and Uranus were incorrect, according to research led by UK astronomers.
Images from a space mission in the 1980s revealed that Neptune is a deep blue and Uranus is green.
However, a study found that the two ice giant planets have similar shades of greenish blue.
It has been revealed that previous images of Neptune were enhanced to show details of the planet’s atmosphere, altering its true color.
“They tweaked the colors, which I think everyone on Instagram has done at some point in their lives,” Prof Catherine Heymans, Astronomer Royal for Scotland and a University of Edinburgh astrophysics professor, told BBC Radio 4’s Today.
“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 pretty similar to Uranus.”
According to Prof Patrick Irwin of the University of Oxford, who led the research, astronomers have long known that most modern images of the two planets do not accurately reflect their true colors.
“Even though the artificially saturated color was known at the time amongst planetary scientists – and the images were released with captions explaining it – that distinction had become lost over time.”
According to Dr. Robert Massey, deputy director of the Royal Astronomical Society (RAS), image enhancement is standard procedure in astronomical research.
“It would be foolish to look at an astronomy image and not suspect that it has been enhanced.” They must be because that is how they are processed to see things.
“It’s not that there was an arrangement to hide it from the public!”
Prof Irwin and his colleagues processed the original data to create what they claim is the ”most accurate representation yet” of the colors of Neptune and Uranus.
The initial misunderstanding arose as images captured of both planets by NASA’s Voyager 2 spacecraft mission were recorded in three distinct colors.
The images were recombined to create composite color images, which were not always evenly balanced. The contrast was also heavily boosted to bring out details in the planets’ clouds, bands, and winds. Both processes made Neptune appear bluer than it was.
The data used in the recent study came from the Hubble Space Telescope Imaging Spectrograph and the Multi Unit Spectroscopic Explorer on the European Southern Observatory’s Very Large Telescope.
Each pixel in both instruments is a continuous spectrum of colors, allowing the researchers to produce the true colors of both planets.
Uranus and Neptune are both a similar shade of greenish blue, according to the analysis, though there is a slight difference. Neptune has a slight hint of extra blue, which the model explains is due to a thinner haze layer on that planet.
The study also discovered that Uranus appears greener during the summer and winter seasons when one of its poles is pointed toward the Sun. However, when the Sun is over the equator in the spring and autumn, it has a bluer tinge.
The findings were published in the RAS Monthly Notices.