The Hubble Space Telescope has captured the birth of one of Neptune’s mysterious short-lived storms, which can grow to be larger than planet Earth before dying out in a matter of years.
Giant storms dubbed the Great Dark Spot and Dark Spot 2 were first observed on Neptune in 1989 during the Voyager 2 flyby.
But, when Hubble attempted to take a look at the same features just five years later, in 1994, both of the massive storms were gone.
Though similar storms observed on other planets are thought to persist for upwards of 100 years, such as Jupiter’s famous Great Red Spot, recent observations suggest storms crop up on Neptune roughly every five years and survive for about as long.
Scroll down for video
Giant storms dubbed the Great Dark Spot (pictured on right, seen at the center of the planet) and Dark Spot 2 were first observed on Neptune in 1989 during the Voyager 2 flyby. More recently, NASA spotted bright white methane clouds sitting above another spot (left)
When scientists directed Hubble toward Neptune’s large storms in the 1990s, they never expected they would no longer be there.
‘It was certainly a surprise,’ said Amy Simon, a planetary scientist at NASA’s Goddard Space Flight Center in Maryland.
‘We were used to looking at Jupiter’s Great Red Spot, which presumably had been there for more than a hundred years.’
To further investigate, the Outer Planet Atmosphere Legacy (OPAL) project has been analyzing Hubble’s Neptune images on a yearly basis since 2015, tracking a small storm in the southern hemisphere.
But last year, they spotted a new dark spot just north of the equator. The team says it’s roughly the same size as the Great Dark Spot, which grew to about 13,000 kilometers by 6,600 km (approximately 8,000 miles by 4,100 miles).
‘We were so busy tracking this smaller storm from 2015, that we weren’t necessarily expecting to see another big one so soon,’ Simon said.
‘That was a pleasant surprise. Every time we get new images from Hubble, something is different than we expected.’
The team looked back on the images captured between 2015 and 2017 and discovered small white clouds in the region where the dark spot later appeared.
According to NASA, these clouds are made up of methane ice crystals and sit high in the atmosphere above the darker material.
The researchers estimate new storms appear every four to six years, and linger for as long as six years.
For the most part, though, storms likely last about two years.
The team looked back on the images captured between 2015 and 2017 and discovered small white clouds in the region where the dark spot later appeared (shown)
This is based on simulations using 256 archival images from Hubble and Voyager 2 accounting for 8,000 total dark spots observed over the years.
About 85 to 95 percent of storms had a two-year lifespan.
Moving forward, researchers are hoping to investigate how the shape of the storms’ vortex and wind speed changes.
‘We have never directly measured winds within Neptune’s dark vortices, but we estimate the wind speeds are in the ballpark of 328 feet (100 meters) per second, quite similar to wind speeds within Jupiter’s Great Red Spot,’ said Michael Wong, a planetary scientist at the University of California, Berkeley.
Much about the conditions on Neptune remain a mystery. But, scientists say unlocking its secrets could help us understand planets outside of our own solar system, too.
‘If you study the exoplanets and you want to understand how they work, you really need to understand our planets first,’ Simon said.
‘We have so little information on Uranus and Neptune.’
‘The more you know, the more you realize you don’t know,’ Orton said.
WHAT IS THE HUBBLE SPACE TELESCOPE?
The Hubble telescope was launched on April 24, 1990, via the space shuttle Discovery from Kennedy Space Centre in Florida.
It is named after famed astronomer Edwin Hubble who was born in Missouri in 1889.
He is arguably most famous for discovering that the universe is expanding and the rate at which is does so – now coined the Hubble constant.
Hubble has made more than 1.3 million observations since its mission began in 1990 and helped publish more than 15,000 scientific papers.
The Hubble telescope is named after Edwin Hubble who was responsible for coming up with the Hubble constant and is one of the greatest astronomers of all-time
It orbits Earth at a speed of about 17,000 mph in low Earth orbit at about 340 miles in altitude.
Hubble has the pointing accuracy of .007 arc seconds, which is like being able to shine a laser beam focused on Franklin D. Roosevelt’s head on a dime roughly 200 miles away.
Hubble’s primary mirror is 2.4 meters (7 feet, 10.5 inches) across and in total is 13.3 meters (43.5 feet) long – the length of a large school bus.
