Images taken by Hubble Space Telescope document the formation of a large dark place on Neptune for the first time, reporting on researchers in a new study.
Like Jupiter's Great Red Spot, Neptune's Great Dark Spaces are storms that form high atmospheric pressure areas. In contrast, storms on the Earth form around areas of low pressure.
Scientists have seen a total of six dark places on Neptune over the years. Voyager 2 identified two storms in 1989. Since Hubble launched in 1990, he has seen four more of these storms.
In the new study, planetary scientists analyzed Hubble's pictures of the ice giant taken over the last few years and recorded the growth of a new Great Dark Spot which became visible in 2018.
By studying companion clouds that showed two years before the new Dark Great Spot, the researchers come to the conclusion that dark spots originate much deeper in Neptune's atmosphere than was thought of before.
Hubble's images also helped the researchers identify how often Neptune gets dark places and how long they last. The new findings give scientists an insight into the inner workings of the huge blurred ice planets but they also have implications for the study of similar sized and similar outflows.
"If you are studying the outlets and you want to understand how they work, you need to understand our planets first," says Amy Simon, a planetary scientist in Wales. NASA Goddard Space Flight Center at Greenbelt, Maryland and lead author of the new study. today in AGU magazine Geophysical Research Letters. "We have so much information about Uranus and Neptune."
History of dark places
Scientists first saw Great Wild Day in Neptune in 1989, when a NASA Voyager 2 probe flew past the mysterious blue planet. As the spacecraft magnified, he drew pictures of two large storms brewing in the Neptune hemisphere. Scientists called the storms in "The Great Dark View" and "Dark Scenes 2."
Five years later, Hubble Space Telescope took sharp images of Neptune which revealed that the Great Dark Spot of the Earth's size and the smaller Dark Spectrum 2 had disappeared.
"It was certainly a surprise," Simon said. "We used to look at Great Red Spot Jupiter, which had been there for over a hundred years."
New Great Smot appeared on Neptune in 2018, almost exactly the same size as the one Voyager seen in 1989. Simon and his colleagues analyzed Hubble's images of a smaller dark spot that appeared in 2015 when bright white clouds were found in the region where 2018 Great Dark Spot would appear later.
"We were so busy tracing this smaller storm from 2015, that we didn't necessarily expect another one so soon," said Simon.
The high altitude clouds include methane ice crystals, giving them their distinctive bright white color. Scientists suspect that these methane clouds coincide with the storms that form dark spots, hovering above the way lenticular clouds cap tall mountains on Earth.
The life of the van and the place
Simon and fellow writers Michael Wong and Andrew Hsu at the University of California Berkeley traced the methane clouds from 2016 to 2018. They thought the clouds were brightest in 2016 and 2017, before the New Dark Spot becomes visible.
The computer models of Neptune's atmosphere have shown the deeper the storm, the brighter clouds. That these white clouds had appeared two years before the Great Dark Spot and that they had lost some brilliance when it became clear that dark spaces could become much deeper in Neptune's atmosphere than thought of front, according to the new study.
Simon, Wong and Hsu also used images of Hubble and Voyager 2 to indicate how long these storms last and how often they occur. They reported in a second study published today in the Astronomical Astronomy that they suspect that new storms are rising on Neptune every four to six years. Each storm can last up to six years, although the lifespan of two years is more likely, according to the findings.
Red against Red
The new findings show how Neptune's big dark spots differ from Jupiter's big red spot. The Great Red Spot was seen for at least 1830 and could be up to 350 years old. Thin jet streams on Jupiter keep the Great Red Spot from breaking apart and changing latitude; it's rotated around Ipiter but it's not moving to the north or south.
But Neptunian winds operate in much wider bands around the planet, so storms like the Great Dark Spot slow down slowly across latitudes. These storms usually hover between western equatorial wind jets and blow currents to the east in the higher latitudes before strong winds pull them apart.
Planetary scientists hope the next study will change the shape of the fortune and wind speed in storms that form dark places. "We have never measured winds directly within Neptune's dark ports, but we estimate that the wind speed in the ball plot of 328 feet (100 meters) per second, is quite similar to wind speed within the Great Red Spot Ipiter, "Wong said. More frequent observations using Hubble will help paint a clearer picture of how storm systems on Neptune evolve, he said.
This paper is available free through April 30. Journalists and public information officers (PIOs) can download a PDF copy of the article by clicking on this link: https: //agupubs.onlinelibrary.wiley. com / doi / full / 10.1029 / 2018GL080658
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