If you thought the planet Neptune was a deep blue color, turns out you're wrong

• Neptune, long believed to be dark blue, is actually very pale like Uranus, scientists say.
• They used modern telescopes to re-assess artificially enhanced images taken by NASA's Voyager 2 probe.

Neptune isn't the rich royal blue it was believed to be for decades, scientists say.

The study by physicists at the University of Oxford found that the eighth planet in our solar system is in fact a delicate powder blue color, very similar in tone to its neighbor Uranus.

For decades, famous images from NASA's Voyager 2 mission have circulated showing Neptune in a deep azure tone. But those enhanced images have resulted in a misconception, the scientists say.

During its closest approach to Neptune in 1989, Voyager 2 gathered images in separate colors, which were then recombined into composites that didn't always reflect the "true" color of the planet, the Oxford scientists explained.

They said the contrast was also amped up to emphasize distinctive features like the planet's bands and clouds.

This meant that Neptune has long appeared "artificially too blue," said the study's lead author, Prof. Patrick Irwin.

"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," he said.

Voyager 2's images of Uranus, from 1986, however, were published in a form closer to "true" color, he added.

"Uranus is still bland and rather boring looking, but Neptune looks fairly washed-out as well when you do the full true color reconstruction," Irwin told The Guardian.

The findings came after the scientists used imaging data from Hubble Space Telescope's Space Telescope Imaging Spectrograph (STIS), and the Multi Unit Spectroscopic Explorer (MUSE) on the European Southern Observatory's Very Large Telescope.

These were then used to re-process the Voyager 2 images. This, they argue, produces a much more accurate sense of how a planet would look to the naked eye.

Using the same process as for Neptune, the study's authors were able to confirm that Uranus remains the same delicate pale blue it was always believed to be. Neptune is just a touch bluer, which the researchers attribute to a thinner haze layer on the planet.