These composite images from the Hubble Space Telescope and the Voyager 2 spacecraft show the newest dark spot to be discovered (left) and the one previously seen in 1989.

(Credits: NASA/ESA/GSFC/JPL)

At a Glance

NASA scientists studied images of Neptune from the Hubble Space Telescope to track the storm's formation.The swirling dark mass is one of six observed so far on the icy planet.Scientists hope their findings will lead to further research about distant planets.

For the first time, scientists have observed the creation of a swirling dark spot on Neptune, gaining new insight into how these giant spinning storms with winds up to 1,500 mph are formed on the icy planet.

And, they say, the findings will help them learn even more about the mysterious planet in the future.

, according to a report on NASA's website, and is the sixth such storm to be seen on Neptune.

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Known as the "Ice Giant," Neptune is the eighth and most distant planet in our solar system. The planet is shrouded in darkness most of the time and wracked by icy supersonic winds. It's the only planet that can't be viewed from Earth by the naked eye.

So how did scientists witness the massive storm's formation?

NASA's Voyager 2 space probe captured the first two known "great dark spots" on Neptune during a flyby in 1989. Later, scientists noted in images from the Hubble Space Telescope that one of those spots had disappeared, so they began constructing computer models to find out why.

NASA's project, known as OPAL, took the idea one step further by studying images of Neptune captured each year by Hubble. The team had been monitoring a smaller spot since 2015, but last year, they noticed a new, more interesting area of development.

"We were so busy tracking this smaller storm from 2015 that we weren't necessarily expecting to see another big one so soon," Amy Simon, a planetary scientist at NASA's Goddard Space Flight Center and a member of the OPAL team, said in the NASA report. "That was a pleasant surprise. Every time we get new images from Hubble, something is different than what we expected."

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The team went back to analyze photos taken from 2015 to 2017 and realized they could follow the new storm's formation in the images, starting with several small, white clouds.

Simon and two of her colleagues this week in the scientific publication Geophysical Research Letters.

They explained that the presence of the smaller clouds over several years indicates that Neptune's dark spots may take longer to form than previously thought, which could mean they start deeper in the atmosphere than the scientists who have been creating computer models thought.

"Future computer simulations of Neptune's dark storms can be constrained by these new observations to teach us more about deep atmosphere conditions and processes on all the giant planets," the team said in the paper.

Simon and her fellow researchers hope the new discovery will not only lead to more research and answers about Neptune, but also other distant planets.