One of the most spectacular storms in the solar system is changing colour.
Once big enough to swallow three Earths, Jupiter’s ‘Great Red Spot’ is shrivelling at a rate of 140 miles (230km) per year, driving its cloud tops upwards, according to a new Nasa study.
Chemicals that give the oval-shaped storm its reddish hue are being lifted to higher altitudes, which may explain why the spot is gradually a more intense orange, researchers said.
Scientists believe the storm is likely to disappear altogether within 20 years.
Jupiter’s ‘Great Red Spot’ has is shrivelling at a rate of 140 miles (230km) per year, driving its cloud tops upwards. Chemicals that give the storm its reddish hue are being lifted to higher altitudes, which could be turning the spot orange. Researchers suggest the spot has gradually deepened in colour since 2014
Scientists suggest the changes are the result of the storm’s shifting winds, which reach speeds of 425 miles per hour (680kph) as they push Jupiter’s crimson clouds counterclockwise around the planet’s southern hemisphere.
‘Storms are dynamic, and that’s what we see with the Great Red Spot. It’s constantly changing in size and shape, and its winds shift, as well,’ said Dr Amy Simon, an expert in planetary atmospheres at Nasa’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the new paper.
Observations of Jupiter date back centuries, but the first confirmed sighting of the Great Red Spot was in 1831.
Keen observers have long been able to measure the size and drift of the Great Red Spot by fitting their telescopes with an eyepiece scored with crosshairs.
A continuous record of at least one observation of this kind per year dates back to 1878.
The Nasa team combined these observations with data from Nasa spacecraft that have visited Jupiter, from Voyager in 1979, to Galileo in 1995, up to the ongoing Juno mission, which reached the planet’s orbit in July 2016.
Scientists suggest the changes are the result of the storm’s shifting winds, which reach speeds of 425 miles per hour (680kph) as they push Jupiter’s crimson clouds counterclockwise around the planet’s southern hemisphere
Observations of Jupiter date back centuries, but the first confirmed sighting of the Great Red Spot was in 1831. The Nasa team combined these observations with data from Nasa spacecraft that have visited Jupiter, from Voyager in 1979, to Galileo in 1995, up to the ongoing Juno mission, which reached the planet’s orbit in July 2016
WHAT IS JUPITER’S GREAT RED SPOT?
Jupiter’s Great Red Spot is a giant oval of crimson-coloured clouds in Jupiter’s southern hemisphere that race counterclockwise around the oval’s perimeter.
The biggest storm in the solar system, it appears as a deep red orb surrounded by layers of pale yellow, orange and white.
Trapped between two jet streams, the Great Red Spot is an anticyclone swirling around a centre of high atmospheric pressure that makes it rotate in the opposite direction to hurricanes on Earth.
Jupiter’s Great Red Spot is a giant oval of crimson-coloured clouds in Jupiter’s southern hemisphere that race counterclockwise around the oval’s perimeter
Winds inside the storm have been measured at several hundreds of miles per hour, with wind storms greater than any storm on Earth, Nasa astronomers have said.
In the late 1800s it was estimated to be about 35,000 miles (about 56,000 km) in diameter – wide enough for four Earths to fit side by side.
Measuring 10,000 miles (16,000 kilometres) wide as of April 3, 2017, the Great Red Spot is 1.3 times as wide as Earth and is gradually shrinking over time.
They analysed the spot’s size, shape, colour and drift rate alongside the storm’s internal wind speeds, when that information was available from spacecraft.
The study shows the storm has been shrinking since 1878 and is now big enough to accommodate just over one Earth. In the 1800’s it was wide enough for four Earths to fit side by side.
But what the huge spot is losing in girth, it is gaining in height.
By measuring how the storm reflected ultraviolet light over several decades, the team concluded that its cloud tops are getting higher.
The researchers analysed the spot’s size, shape, colour and drift rate alongside the storm’s internal wind speeds, when that information was available from spacecraft
The study shows the storm has been shrinking since 1878 and is now big enough to accommodate just over one Earth. In the 1800’s it was wide enough for four Earths to fit side by side
Because the storm has been contracting, the researchers expected to find the already-powerful internal winds becoming even stronger, like an ice skater who spins faster as she pulls in her arms.
But instead of accelerating, the storm appears to be forced to stretch up.
‘It’s almost like clay being shaped on a potter’s wheel,’ Nasa said in a statement.
‘As the wheel spins, an artist can transform a short, round lump into a tall, thin vase by pushing inward with his hands. The smaller he makes the base, the taller the vessel will grow.’
A researcher with the Juno mission says that the Great Red Spot has been shrinking for a long time and is only 1.3 times the size of Earth, whereas in the late 1800s it was the width of four Earths
Tom Momary posted this version of an image of the Great Red Spot, titled ‘Peering into the Great Red Spot…color enhancements and vibrance, to bring out detail’. Juno took images if the Great Red Spot in July 2017 and will again be able to spot the Great Red Spot in April 2018, as well as in July and September of 2019, and one last time in December 2020
The Great Red Spot’s colour has been deepening, too, becoming intensely orange since 2014.
Researchers aren’t sure why this is happening, but it’s possible the chemicals that give the storm its reddish hue are being carried higher into the atmosphere as the spot stretches up.
At higher altitudes, the chemicals are subjected to more UV radiation and would take on a deeper colour.
Researchers said they don’t know whether the spot will shrink a bit more and then stabilise, or break apart completely.
The Great Red Spot’s colour has been deepening, too, becoming intensely orange since 2014. Researchers aren’t sure why this is happening, but it’s possible the chemicals that give the storm its reddish hue are being carried higher into the atmosphere as the spot stretches up
Trapped between two jet streams, the Great Red Spot is an anticyclone swirling around a centre of high atmospheric pressure that makes it rotate in the opposite sense of hurricanes on Earth. Nasa’s Juno spacecraft passed about 5,600 miles (9,000 kilometers) above the Giant Red Spot clouds in July of 2017
‘If the trends we see in the Great Red Spot continue, the next five to 10 years could be very interesting from a dynamical point of view,’ said Nasa Goddard centre scientist and study co-author Dr Rick Cosentino.
‘We could see rapid changes in the storm’s physical appearance and behaviour, and maybe the red spot will end up being not so great after all.’
Jupiter’s Great Red Spot is a giant oval of crimson-colored clouds in Jupiter’s southern hemisphere that race counterclockwise around the oval’s perimeter with wind speeds greater than any storm on Earth.
Dr Glenn Orton, a Juno mission team member and a planetary scientist at NASA JPL, told Business Insider last month that the Great Red Spot is like a ‘spinning wheel that keeps on spinning because it’s caught between two conveyor belts that are moving in opposite directions.
‘The GRS is stable and long-lived, because it’s ‘wedged’ between two jet streams that are moving in opposite directions.’
But Dr Orton warned its days are numbered. ‘In truth, the GRS has been shrinking for a long time,’ he said.
‘The GRS will in a decade or two become the GRC (Great Red Circle),’ Orton said. ‘Maybe sometime after that the GRM’ – the Great Red Memory.
WHAT WAS NASA’S JUNO MISSION TO JUPITER?
The Juno probe reached Jupiter last year after a five-year, 1.8 billion-mile journey from Earth
The Juno probe reached Jupiter on July 4, 2016, after a five-year, 1.8 billion-mile journey from Earth.
Following a successful braking manoeuvre, it entered into a long polar orbit flying to within 3,100 miles (5,000 km) of the planet’s swirling cloud tops.
The probe will skim to within just 4,200 km of the planet’s clouds once a fortnight – too close to provide global coverage in a single image.
No previous spacecraft has orbited so close to Jupiter, although two others have been sent plunging to their destruction through its atmosphere.
To complete its risky mission Juno will have to survive a circuit-frying radiation storm generated by Jupiter’s powerful magnetic field.
The maelstrom of high energy particles travelling at nearly the speed of light is the harshest radiation environment in the Solar System.
To cope with the conditions, the spacecraft is protected with special radiation-hardened wiring and sensor shielding.
Its all-important ‘brain’ – the spacecraft’s flight computer – is housed in an armoured vault made of titanium and weighing almost 400 pounds (172kg).