Neptune’s clouds have disappeared, and scientists think they know why

Each planet in the solar system has its own shape. Earth has aquamarine oceans. Jupiter has vertical storms. Saturn has sparkling rings. And Neptune has ghost clouds — at least, it used to. For the first time in three decades, the electric blue orb is completely cloud-free, and astronomers are terrified.

Neptune’s cloud cover is known to ebb and flow. But since October 2019, only one speck of fluffy white has been looping around the planet’s south pole.

“It was the first time anyone had ever seen this,” he said. Emky de Pater, an astronomer at the University of California, Berkeley. “There is nothing there. What is going on here?”

To break through the state of the vanishing clouds, scientists have been capturing near-infrared images of Neptune for 30 years using ground-based observatories and the Hubble Space Telescope. In a study published in June in the journal Icarus, Dr. De Pater and her colleagues are the prime suspect in this cloud clearing: the Sun.

Neptune, a frozen planet riddled with hypersonic storms, has been visited by only one spacecraft, Voyager 2, which launched in 1989. Thus, not much is definitively known about the planet, including its eccentric nature. hydrocarbon clouds.

Until another robotic emissary appears to greet Neptune, astronomers must rely on telescopes to decipher its secrets. Interested in the half-naked pose of the ice giant, a team led by Andy Chaveznow a graduate student at the Harvard-Smithsonian Center for Astrophysics, is about to work.

The researchers combined images taken by Hubble, the Keck Observatory in Hawaii, and the Lick Observatory in California to create a 29-year album of images of Neptune going back to 1994. They then compared it to the sun’s cycles.

The Sun goes through cycles of hyperactivity and lull, lasting from eight to 14 years, driven by the frequent reversal of the Sun’s magnetic field. these courses It appears to rise and fall in sync with Neptune’s cloud cover. In 2002 and 2015, for example, Neptune displayed countless clouds, hot on the heels of peak solar activity on both occasions. The bombardment of ultraviolet light is thought to trigger a chemical reaction that creates clouds in the planet’s ethereal sky.

Conversely, during perihelion, Neptune’s vapor veil thins—although it is not known why the current scarcity of clouds is so extreme compared to previous cycles.

she has He was Proposal That these two extremely distant celestial bodies might be connected in this way is improbable. But this study provides the strongest evidence yet that Neptune’s cloudy fashion can be attributed to a solar flare, indicating the ice giant’s nebulous dynamic.

“Ultraviolet emission from the sun can dictate the structure of Neptune’s clouds like an orchestra conductor giving directions to a lone violinist 2.8 billion miles away,” he said. Grant Tremblay, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics who was not involved in this work. “It’s further evidence that our sun really is the master of the solar system, even in its farthest reaches.”

Heidi HamillAlso praising the results, he is a planetary astronomer and vice president of science at the Association of Universities for Research in Astronomy who was not involved in the study.

“One of the things I’ve always enjoyed about studying Neptune is that it’s never quite the same,” she said. “This study helps us better understand why that is.”

But a handful of solar cycles is not enough to understand the mechanism that creates these clouds, nor can it confirm that the relationship between the two represents causation. Scientists eagerly anticipate the next solar maximum, Predictions for the year 2025Curious to see if the planet’s clouds will bloom soon after.

“With exoplanets like Neptune and Uranus, you have to play the long game,” said Dr. Hamill.