Neptune prides itself on some of the strangest weather in the solar system. The eighth planet of the Sun holds the record for the fastest winds observed in any world, with speeds that cross the atmosphere upwards of 1,100 miles per hour, or 1.5 times the speed of sound. Scientists still don’t know exactly why its atmosphere is so tumultuous. Their last look at Neptune offered even more reason to be confused.
© NASA, ESA, STScI, MH Wong, LA Sromovsky and PM Fry
The Hubble Space Telescope identified a storm in 2018, a dark spot about 4,600 miles wide. From that moment, it seems to have headed towards the equator, but then descended back north, according to the latest Hubble observations. It also has a smaller accompanying storm, nicknamed Dark Spot Jr., which scientists believe could be a piece that broke the main storm. These ink vortices stand out against the dizzying blue sky of the planet, but although they are blinding to see, their lifespan is short, which makes them even more difficult to study.
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It’s not the first time Neptune’s dark spots have behaved so strangely. When the Voyager 2 spacecraft flew over the planet in 1990, (still the only spacecraft to do so) it noticed two storms. One was the original Dark Spot, a large vortex the size of Earth. She, too, had a companion, a smaller, fast-moving storm, nicknamed the Scooter. The first Dark Spot observed also seemed to move south and then back north.
“When I was watching the big dark spot with Voyager, I saw it oscillating up and down in longitude,” said Heidi Hammel, a member of the Voyager 2 spacecraft’s imaging team and currently vice president of science at the University Research Association. astronomy. “We had enough time on Voyager to be able to follow this function for four to five months before the flight. That storm was huge, a big monster “, as big as planet Earth.
But by the time Voyager was able to gain time with the Hubble Telescope to observe the storms again, about four years later, they disappeared. Astronomers estimate that the average lifespan of a storm in Neptune is between two and five years, and its longevity could depend on its size. This is a contrast to Jupiter’s Great Red Spot, the other best-known storm in our outer solar system, which sometimes shrinks but has been steadily stirring for at least hundreds of years.
Neptune’s dark vortices sink deep into the planet – imagine them as the canopy of a very tall tree, with roots that stretch to the frozen core of the world. This long connection can move the storm in all directions, allowing it to move south with the winds or retreat north. But as these big storms head south to the equator of the planet, where the wind fields are even stronger, they can tear.
Because astronomers get only one blow a year to use Hubble to look at Neptune, it’s hard to really monitor the temperamental atmosphere. So until scientists notice new storms, we only have a few chances to observe them before they disappear.
“The whole idea that they’re disappearing is one of the most puzzling things about them,” Dr. Hammel said.
Until humans can get an orbit around the planet to better understand the life cycle of these storms, we are left with more questions than answers about this blue beauty. Will Dark Spot and Dark Spot Jr. survive? Come back in 2021 to find out.
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