Uranus and Neptune have way more similar colors than we thought, study shows

Jan 10, 2024

Dunja Djudjic

Dunja Djudjic is a multi-talented artist based in Novi Sad, Serbia. With 15 years of experience as a photographer, she specializes in capturing the beauty of nature, travel, and fine art. In addition to her photography, Dunja also expresses her creativity through writing, embroidery, and jewelry making.

Uranus and Neptune have way more similar colors than we thought, study shows

Jan 10, 2024

Dunja Djudjic

Dunja Djudjic is a multi-talented artist based in Novi Sad, Serbia. With 15 years of experience as a photographer, she specializes in capturing the beauty of nature, travel, and fine art. In addition to her photography, Dunja also expresses her creativity through writing, embroidery, and jewelry making.

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uranus neptune true colors

For decades, we’ve seen stunning images of Neptune as a deep azure and Uranus as a pale cyan. However, it turns out those vibrant colors might not be entirely accurate. A new study reveals that these two ice giants are actually much closer in color than we thought – a shade of greenish-blue, to be precise.

Neptune’s true color

This misconception stems from how images of the planets were captured and processed in the past. Single-color images from Voyager 2 and other missions were combined into composite color images. However, these often had inaccurate color balancing and an overly blue tint in Neptune’s case. Even the iconic Voyager 2 images were enhanced to highlight cloud details, further distorting their true colors.

Professor Patrick Irwin from the University of Oxford led the recent study revealing Neptune’s true colors. Using data from Hubble and other telescopes, he and his team were able to re-balance the color images and reveal their true greenish-blue hue. Neptune still has a slightly bluer tinge due to its thinner haze layer. Still, the overall difference is much subtler than previously thought.

 “Applying our model to the original data, we have been able to reconstitute the most accurate representation yet of the color of both Neptune and Uranus,” Professor Irwin said in a statement.

uranus neptune true colors
Voyager 2/ISS images of Uranus and Neptune released shortly after the Voyager 2 flybys in 1986 and 1989, respectively, compared with a reprocessing of the individual filter images in this study to determine the best estimate of the true colours of these planets. Credit: Patrick Irwin

Another mystery solved

The study also solves the mystery of Uranus’s slight color change during its 84-year orbit. It turns out this is due to a combination of several factors. One is the planet’s unusual spin, as it rotates almost on its side. This results in seasons where one pole points directly towards the Sun. Another reason is that Uranus’ polar regions are less reflective at blue wavelengths and more reflective at green and red wavelengths, partly due to lower methane abundance. Finally, a thickening layer of methane ice particles forms over the sunlit pole during summer, further increasing green and red reflectance.

“This is the first study to match a quantitative model to imaging data to explain why the colour of Uranus changes during its orbit,” Professor Irwin said. “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.”

uranus neptune true colors
Uranus as seen by HST/WFC3 from 2015-2022. During this sequence the north pole, which has a paler green colour, swings down towards the Sun and Earth. In these images the equator and latitude lines at 35N and 35S are marked. Credit: Patrick Irwin

Commenting on the study, Dr. Heidi Hammel, a Neptune and Uranus expert, said that the misperception of Neptune’s color and the unusual color changes of Uranus “have bedevilled us for decades.” But Professor Irwin’s comprehensive study “should finally put both issues to rest.”

But you never know… Maybe future missions will reveal even more about their true colors and secrets.

[via Space.com]

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Dunja Djudjic

Dunja Djudjic

Dunja Djudjic is a multi-talented artist based in Novi Sad, Serbia. With 15 years of experience as a photographer, she specializes in capturing the beauty of nature, travel, and fine art. In addition to her photography, Dunja also expresses her creativity through writing, embroidery, and jewelry making.

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