Each planet in the solar system has its own unique appearance. There are aquamarine oceans on Earth. Jupiter has panchromatic storms. Saturn has twinkling rings. And Neptune has ghostly clouds — at least it used to. For the first time in 30 years, the electric blue orb is nearly cloudless and astronomers are terrified.
Neptune’s cloud cover is known to ebb and flow. But since October 2019, only one faint white speck has been floating around Earth’s South Pole.
“It was the first time anyone had seen this,” he said. Imke de Patel, an astronomer at the University of California, Berkeley. “There’s nothing there. What’s the matter?”
To uncover the truth about the disappearance of clouds, scientists examined 30 years of near-infrared images of Neptune made by ground-based observatories and the Hubble Space Telescope. A study published in June in the journal IcarusDr. de Pater and colleagues have identified the Sun as the prime suspect in this cloud cleansing.
Neptune, a frigid planet shrouded in supersonic storms, was visited only by a single spacecraft, Voyager 2, in 1989, when it passed at high speed. As such, little is known definitively about the planet, including the nature of its eccentric bodies. hydrocarbon cloud.
Until another robotic messenger comes to greet Neptune, astronomers must rely on telescopes to decipher its secrets. Teams interested in the ice giant’s near-naked state Elandi Chaveznow a graduate student at the Harvard-Smithsonian Center for Astrophysics, has started a job.
The researchers combined images taken by Hubble, the Keck Observatory in Hawaii, and the Lick Observatory in California to create a photo album of Neptune spanning 29 years, starting in 1994. Then they compared it with the cycle of the sun.
The Sun experiences cycles of hyperactivity and quiescence lasting 8 to 14 years, caused by repeated reversals of the Sun’s magnetic field.these cycle It seems to rise and fall in sync with Neptune’s cloud cover. For example, in 2002 and 2015, in both cases, just after the peak of solar activity, Neptune showed a myriad of clouds. Ultraviolet radiation is thought to trigger an alchemical reaction that creates clouds in the planet’s fantastical skies.
Conversely, during the Sun’s nadir, Neptune’s vapor veil fades, but it’s unclear why the current cloud deficit is so extreme compared to previous cycles.
it has was done was suggested It seems unlikely that these two very distant objects could be linked in this way. But the study provides the strongest evidence yet that Neptune’s cloudy appearance can be attributed to solar flares, suggesting the mysterious dynamism of the ice giants.
“The idea that ultraviolet radiation from the sun can dictate the structure of Neptune’s clouds is like an orchestra conductor giving instructions to a lone violinist 2.8 billion miles away,” he said. Ta. Grant Tremblaywas an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, but was not involved in the study. “This is another example of how our sun is truly the master of the solar system, even at its most distant reaches.”
Heidi HummelThe scientific vice-president of the Association of Astronomical Research Universities, a planetary astronomer who was not involved in the study, also praised the discovery.
“One of the things I always enjoy about studying Neptune is that it never looks the same,” she said. “And this study helps us better understand why.”
But just a few solar cycles aren’t enough to understand the mechanisms that give rise to these clouds, nor to confirm that the correlation between the two indicates causation. . Scientists are eagerly anticipating the next solar maximum. Forecast for 2025wants to know if the planetary cloud will bloom soon.
“For exoplanets like Neptune and Uranus, you have to play the long game,” says Dr. Hummel.