NASA captured the detailed snapshot of the Neptunian dark spot earlier in September and November 2018 with the Hubble Wide Field Camera. The mystery blob is the sixth of its kind to suddenly appear on Neptune since NASA first observed the phenomenon 30 years ago. In 1989, NASA’s historic Voyager 2 spacecraft flew past Neptune and snapped images of two dark spots in the planet’s southern hemisphere. Scientists dubbed the incredible discovery “The Dark Spot” and “The Dark Spot Two”.
Just five years later, in 1994, NASA directed the Hubble telescope at Neptune but was disappointed to find the dark spots vanished.
Amy Simon, a planetary scientist at NASA’s Goddard Space Flight Center, said: “It was certainly a surprise.
“We were used to looking at Jupiter’s Great Red Spot, which presumably had been there for more than a hundred years.”
The dark spots on Neptune were found to be monstrous storms brewing in the frozen planet’s harsh atmosphere.
And today (March 25), NASA has revealed in a new study the atmospheric processes, which lead to the creation of these incredible storms.
In 2015, NASA’s Outer Planet Atmosphere Legacy project (OPAL) carefully observed a dark spot on Neptune until it gradually disappeared from sight.
But then in 2018, a completely new spot emerged on Neptune, which for the first time in the history of space exploration, was observed by astronomers.
The new storm was found to measure an incredible 8,000 miles by 4,100 miles (13,000km by 6,600km).
On its longest side, the storm is roughly as wide as the Earth is and is comparable in size to Jupiter’s famous Great Red Spot.
It was certainly a surprise
Amy Simon, NASA
Dr Simon said: “We were so busy tracking this smaller storm from 2015, that we weren’t necessarily expecting to see another big one so soon.
“That was a pleasant surprise. Every time we get new images from Hubble, something is different than what we expected.”
The storm’s birth was caught on camera when scientists analysed Hubble photos ranging from 205 to 2015.
The scientists found evidence of small white clouds forming in the same region where the new dark spot would appear.
The findings were published on Monday, March 25, in the science journal Geophysical Research Letters.
The exact conditions inside of the Neptune storm will likely remain a mystery but astronomers have a good idea of what is happening.
Michael Wong, a planetary scientist at the University of California, said: “We have never directly measured winds within Neptune’s dark vortices, but we estimate the wind speeds are in the ballpark of 329 feet (100m) per second, quite similar to wind speeds within Jupiter’s Great Red Spot.”
NASA is hopeful the findings will help astronomers better understand the atmospheric processes on distant exoplanets where NASA is searching for signs of life.
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