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Astronomers have been unraveling the mysteries of Neptune, and now they think they’ve figured it out.
The Ice Giant’s ghostly cirrus-like clouds all but disappeared four years ago. Currently, only a small portion floats above the South Pole of the Earth.
Scientists analyzed about 30 years of observations of Neptune taken by three space telescopes and found that the decline in ice giant clouds is synchronized with the solar cycle. announced that it has determined that it may indicate Recent research It was published in Icarus magazine.
“These remarkable data give us the strongest evidence yet that Neptune’s cloud cover is correlated with the solar cycle,” said lead author of the study, UC Berkeley Astronomy. Professor Emeritus Imke de Peyter said. news release. “Our findings support the theory that if the sun (ultraviolet light) is strong enough, it may be triggering photochemical reactions to produce Neptune’s clouds.”
During the solar cycle, the activity level of the Sun’s dynamic magnetic field increases and decreases. According to NASA, the magnetic field is tangled like a ball of yarn and flips every 11 years. As the sun becomes more active, more intense ultraviolet rays fall on the solar system.
Using data from NASA’s Hubble Space Telescope, WM Keck Observatory in Hawaii, and Lick Observatory in California, scientists observed 2.5 cycles of cloud activity over a 29-year observation period of Neptune. Meanwhile, the planet’s reflectance increased in 2002 and faded in 2007. Neptune brightened again in her 2015 and is fainter than it’s ever been seen in 2020. Then most of the clouds disappeared.
“Four years later, the most recent images taken in June of this year still show that the clouds have not returned to their previous levels,” said lead author of the study and PhD student at the Harvard Center for Astrophysics. Elandi Chavez says. According to a statement from the Smithsonian Institution.
The discovery was “very exciting and unexpected, especially since Neptune’s previous periods of low cloud activity were less dramatic and longer,” Chavez added.
The authors also found that two years after the peak of the cycle, more clouds appeared on Neptune, and that the more clouds there were, the brighter Neptune reflected sunlight. According to NASA, the relationship “was surprising to planetary scientists because Neptune is the most distant major planet in the solar system and receives sunlight at about 0.1% of the intensity that Earth receives.” The finding also contradicts the idea that clouds are influenced by Neptune’s four seasons, each lasting about 40 years.
“This is a very interesting paper and a very good piece of good old, detailed detective work,” said Patrick Irwin, professor of planetary physics at the University of Oxford, who was not involved in the study, in an email. Ta. “This new paper covers a longer time frame than previous studies and shows a compelling correlation between observed cloud cover and the sun’s ultraviolet brightness.”
However, there is a two-year time lag between the peak of the solar cycle and the increase in Neptune’s cloud abundance. The authors speculate that this gap could be explained by photochemistry occurring in the upper layers of the planet’s upper atmosphere, where it takes time for clouds to form.
The relationship between increased sun brightness and cloud formation may be due to the production of ionized molecules that can act as cloud condensation nuclei and help initiate condensation, Erwin said.
“It’s interesting to be able to use telescopes on Earth to study the climate of a world more than 2.5 billion miles away from us,” study co-author Carlos Alvarez, an astronomer at the Keck Observatory, said in a statement. Ta. “Technical and observational advances have made it possible to constrain Neptune’s atmospheric model, which is key to understanding the correlation between the ice giant’s climate and the solar cycle.”
The authors say that the researchers continue to monitor Neptune’s cloud activity, as more ultraviolet light could darken Neptune’s clouds and reduce overall brightness.
Additionally, Neptune storms rising from the deep atmosphere affect the cloud cover of the planet, but are not related to clouds forming in the upper atmosphere. That variable could hamper studies examining correlations between photochemically-generated clouds and the solar cycle. Further research may also suggest how long Neptune will remain largely cloudless.
According to NASA, these studies will not only expand astronomers’ knowledge of Neptune, but also give researchers a better understanding of many exoplanets outside our solar system that are believed to have features similar to those of the ice giants. It may also help to
The study also “emphasizes the need to continue monitoring the planets of our solar system,” Erwin said. “Only by observing these planets at regular intervals will it be possible to build long-term, reliable datasets to investigate these periodic variations.”