REPUBLIKA.CO.ID, JAKARTA — In the summer of 1989, the space shuttle Voyager 2 NASA’s property sends the first image of the planet Neptune which humans took via radio to Earth. The images reveal that the outermost planet of the sun is a stunning dark blue planet.
In contrast, Uranus, Neptune’s neighbor and the first planet discovered with a telescope, appears paler. Reported Space, Friday (5/1/2024), these two planets, which appear to be twins, have many similarities. They are roughly the same size, almost the same size, and both are enveloped in an inner atmosphere made of similar materials.
So why do the two planets have different shades of blue? This is a question that has puzzled scientists for decades.
But now, a new analysis of Voyager 2 images shows the two ice giants actually have a similar blue-green color, which is the “most accurate representation” of the planets’ color, the new study finds.
In the late 1900s, picture Uranus and Neptune recorded by Voyager 2 were combined in one color to produce a composite image showing that the planets are greenish blue (cyan) and sky blue (azure) respectively. Although published images of Uranus were processed to approximate its true color, early images of Neptune had been “stretched and enhanced” to reveal its clouds, elongated areas, and winds, “and were therefore artificially rendered too blue,” study lead author Patrick Irwin, said. a planetary physicist at Oxford University in the United Kingdom (UK), said in a statement.
“While artificially saturated colors were known at the time among planetary scientists, and the images were released with captions explaining them, the differences have disappeared over time,” Irwin said.
To address this misconception, Irwin and colleagues used new images from NASA’s Hubble Space Telescope and the European Space Agency’s (ESA) Very Large Telescope, whose instruments capture the rich spectrum of colors in each pixel, so that their processing determines the “true true color” of Uranus and Neptune.
Then, the team revisited the Voyager 2 images and rebalanced them according to the new data, which showed that the two planets are actually a similar blue color. The color comes from the methane layer in the planet’s atmosphere which absorbs the red color from sunlight.
Uranus is slightly whiter, according to the new study, perhaps because its somewhat “stagnant and sluggish” atmosphere allows methane haze to accumulate, which reflects the red portion of sunlight more than Neptune.
The presence of accumulated methane ice particles could also explain why Uranus changed color slightly during its 84-year orbit around the sun. Images recorded between 1950 and 2016 by the Lowell Observatory in Arizona show the planet appearing greener during the solstices, when one of its poles points toward the sun, and bluer during the equinoxes, when the sun shines directly above its equator.
By comparing the brightness of Uranus’ poles with the equatorial regions in these images, Irwin and his team concluded that the amount of methane near the poles may be half as much as at the equator, causing the color changes.
Heidi Hammel of the Association of Universities for Astronomical Research, who was not affiliated with the new study, said misunderstandings about Neptune’s color, as well as Uranus’ unusual changes, have puzzled us for decades.
“This comprehensive study will ultimately resolve both issues,” Hammel said.
This research is described in a paper published Thursday (4/1/2024) in the journal Monthly Notices of the Royal Astronomical Society.
2024-01-05 11:25:38
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