roses are red. Neptune It is dark blue.
That’s why Uranus Isn’t it? Scientists thought.
It is a curious question. Uranus and Neptune, the two outermost planets in our solar system, are ice giants – cold worlds made of gas and ice with similar chemical compositions.
They also don’t differ much in mass, with Uranus being 15 times larger than Earth and Neptune 17 times larger. And both are about four times the size of Earth, with Uranus being slightly larger.
When the same spacecraft encountered Neptune in 1989, it revealed a world with some of the most powerful winds in the Solar System, which whirled through a veritable blue atmosphere, giant storms, and even a mysterious Was stunning with dark spot. Why the difference?
Patrick Irwin, a planetary physicist at the University of Oxford, A.T. UK, and his colleagues developed an answer. They gathered detailed knowledge of each world’s atmosphere using the Gemini North telescope in Hawaii Hubble Space Telescope and other observations.
The two planets are blue because they have methane in their atmospheres, a gas that absorbs the red color of sunlight. But an average layer of methane haze on Uranus appeared to be twice as thick as Neptune’s. It is the presence of this additional fog that generates the various forms.
“This fog looks like some whitewash,” Irwin said. “That’s why Uranus looks lighter than Neptune.”
The research was published Tuesday in the Journal of Geophysical Research: Planets.
Imke de Pater, a planetary scientist at the University of California at Berkeley, said the finding makes sense. “The abundance of methane on the two planets is very similar,” she said. “There’s something to explain the color difference.”
Why Uranus may have a thicker haze layer than Neptune’s may have been the result of a giant impact in its existence, said study co-author Leigh Fletcher, a planetary scientist at the University of Leicester in the UK.
“All of its energy and internal heat source could have been released in that giant collision,” he said. “So what we’re seeing today is a more stable world.”
Both worlds would lose fog as methane ice pulled it into the lower atmosphere, falling as methane ice. But on the more active Neptune, methane ice falls more often, thinning the layer of fog.
Erich Karkoschka, a planetary scientist at the University of Arizona, said he “would not make the assumption,” that Uranus’ collision with another object would explain why it is less active than Neptune. He suggested that the planets could be quite different physically due to differences in their atmospheres.
The work could also explain the origin of Neptune’s huge and mysterious dark spot, Irwin said, which is likely caused by the lack of haze particles caused by the evaporation of hydrogen sulfide ice.
A future Uranus orbiter and atmospheric probe are a priority for NASA, scheduled to launch in the 2030s. They can tell scientists more about haze layers, as with observations James Space Telescope Web,
“There’s still a lot of uncertainty,” Irwin said. “We don’t really know what the particles are made of. The only way to really know what’s going on is to launch investigations into these deep atmospheres.”
Translated by Luiz Roberto M. Gonsalves