Cassini may have crashed into Saturn’s surface, but the latest image it took released by NASA has show the planet’s mysterious giant ‘hexagon’ storm in unprecedented detail.
Astronomers have been baffled by 20,000 mile wide storm for 30 years.
Twice the diameter of the Earth, it spins around the northern polar vortex – seen as a dark spot at the planet’s pole in the image – which is understood to the be eye of a hurricane-like storm, at 220mph.
Saturn’s North pole basks in full sunlight in the latest image from Cassini, showing the planet’s mysterious giant ‘hexagon’ storm in unprecedented detail.
‘Close to the northern summer solstice, sunlight illuminates the previously dark region, permitting Cassini scientists to study this area with the spacecraft’s full suite of imagers,’ said NASA.
Reflected sunlight is the source of the illumination for visible wavelength images such as the one above, the space agency said.
However, at longer infrared wavelengths, direct thermal emission from objects dominates over reflected sunlight.
This enabled instruments that can detect infrared radiation to observe the pole even in the dark days of winter when Cassini first arrived at Saturn and Saturn’s northern hemisphere was shrouded in shadow.
Now, 13 years later, the north pole basks in full sunlight.
The Cassini spacecraft ended its mission on Sept. 15, 2017.
Saturn’s atmosphere is an ever-changing scene of high-speed winds and evolving weather patterns, punctuated by occasional large storms, NASA says.
‘Saturn’s hexagonal polar jet stream is the shining feature of almost every view of the north polar region of Saturn,’ NASA said.
‘The region, in shadow for the first part of the Cassini mission, now enjoys full sunlight, which enables Cassini scientists to directly image it in reflected light.’
‘The north pole of Saturn sits at the center of its own domain,’ NASA said.
‘Around it swirl the clouds, driven by the fast winds of Saturn.’
Saturn’s hexagonal polar jet stream is the shining feature of almost every view of the north polar region of Saturn. The region, in shadow for the first part of the Cassini mission, now enjoys full sunlight, which enables Cassini scientists to directly image it in reflected light.
Although the poles of Saturn are at the center of all of this motion, not everything travels around them in circles.
Some of the jet-stream patterns, such as the hexagon-shaped pattern seen here, have wavy, uneven shapes.
The famous hexagon shape itself circumscribes the northern polar vortex – seen as a dark spot at the planet’s pole in the above image – which is understood to be the eye of a hurricane-like storm.
The rings, consist of countless icy particles, which are continually colliding.
‘Beyond that orbits Saturn’s retinue of moons and the countless small particles that form the ring,’ NASA explained.
The latest image shows Saturn’s north polar region’s bands and swirls, which Nasa says somewhat resemble the brushwork in a watercolor painting.
Each latitudinal band represents air flowing at different speeds, and clouds at different heights, compared to neighboring bands.
Where they meet and flow past each other, the bands’ interactions produce many eddies and swirls.
This stunning new image reveals the massive hexagonal storm at Saturn’s North Pole, and its gigantic rings. Each latitudinal band represents air flowing at different speeds, and clouds at different heights, compared to neighboring bands.
Such collisions play a key role in the rings’ numerous waves and wakes, which are the manifestation of the subtle influence of Saturn’s moons and, indeed, the planet itself.
The long duration of the Cassini mission has allowed scientists to study how the atmosphere and rings of Saturn change over time, providing much-needed insights into this active planetary system.
It has long baffled astronomers, and now the strange hexagon at Saturn’s north pole has a new mystery.
The mysterious six-sided hexagon on Saturn’s North Pole has long captivated astronomer, and is thought to be nearly 20,000 miles (32,190 km) wide.
The hexagon is made of a band of upper-atmospheric winds which creates its shape.
A polar cyclone can be seen at its centre.
Recent natural colour images from NASA’s Cassini spacecraft show the changing appearance of Saturn’s north polar region between 2012 and 2016.
THE ‘GRAND FINALE’
Cassini has circled Saturn for 13 years since reaching its orbit in 2004, spearheading remarkable discoveries about the ringed planet and its icy moons – but now, it’s running low on fuel.
On April 22 the spacecraft began to transition into its grand finale orbits, taking one last close flyby of Saturn’s massive moon Titan.
The first of the spaceship’s 22 deep dives between Saturn and its innermost ring was performed on April 26. Communications with the spacecraft went dark during the dive but have now returned. The craft’s second dive begins today at 8:38pm BST (3:38pm ET). Communications will also go dark during this second dive until May 3
Titan’s gravity bent Cassini’s flight path, causing the orbit to shrink until it was on course to pass between Saturn and the inner edges of its rings.
Cassini began the first of 22 dives through an unexplored gap on April 26.
The second of these dives began on Tuesday at 8:38pm BST (3:38pm ET).
Cassini’s mission will officially terminate on September 15, after a planned plummet through Saturn’s atmosphere.
And all the while it will transmit data from several instruments until the signal is finally lost.
It shows a clear change from blue to gold – and nobody knows why.
Scientists are investigating potential causes for the change in color of the region inside the north-polar hexagon on Saturn.
The colour change is thought to be an effect of Saturn’s seasons.
SATURN’S HEXAGONAL VORTEX
The mysterious six-sided hexagon on Saturn’s North Pole has long captivated astronomer, and is thought to be nearly 20,000 miles (32,190 km) wide.
The hexagon is made of a band of upper-atmospheric winds which creates its shape.
A polar cyclone can be seen at its centre.
The strange hexagonal structure, seen in the animation above from directly over Saturn’s north pole, rotates at the same speed as the planet itself spins on its axis. It is more than 20,000 miles (32,190km) in diameter
First seen by Voyagers 1 and 2 more than 30 years ago, the hexagon it thought to be fixed with Saturn’s rotation.
Last year, the Cassini spacecraft provided scientists with the first close-up, visible-light views of a behemoth hurricane swirling within the hexagon.
Thin, bright clouds at the outer edge of the hurricane were estimated to be travelling at around 330mph (150 metres per second).
‘In particular, the change from a bluish color to a more golden hue may be due to the increased production of photochemical hazes in the atmosphere as the north pole approaches summer solstice in May 2017,’ Nasa said.
Researchers think the hexagon, which is a six-sided jetstream, might act as a barrier that prevents haze particles produced outside it from entering.
During the seven-year-long Saturnian winter, the polar atmosphere became clear of aerosols produced by photochemical reactions – reactions involving sunlight and the atmosphere.
These two natural colour images from NASA’s Cassini spacecraft show the changing appearance of Saturn’s north polar region between 2012 and 2016, showing a clear change from blue to gold.
Since the planet experienced equinox in August 2009, the polar atmosphere has been basking in continuous sunshine, and aerosols are being produced inside of the hexagon, around the north pole, making the polar atmosphere appear hazy today.
Other effects, including changes in atmospheric circulation, could also be playing a role.
Scientists think seasonally shifting patterns of solar heating probably influence the winds in the polar regions.
Both images were taken by the Cassini wide-angle camera.
The unusual geometric structure, which is around 20,000 miles (32,187 km) wide, rotates at almost exactly the same rate as Saturn spins on its axis.
Scientists now believe it is formed by winds, similar to our own arctic jet stream, racing eastwards around the pole at cloud level and being jostled into shape by other winds below it.
An enormous six-sided storm circling Saturn’s north pole (shown in false colour pictured) has a strange geometric shape that may be formed by winds deep in the atmosphere jostling a jet stream at cloud level into shape, according to new research based on computer simulations of the baffling structure on the gas giant
The findings provide a ‘simple’ solution to the properties of the strangely shaped vortex, according to astronomers.
Writing in journal Astrophysical Journal Letters, Professor Raúl Morales-Juberías, a planetary scientist at the New Mexico Institute of Mining and Technology in Socorro, and his colleagues said the key to the shape appeared to be the height of the jet stream.
They constructed computer models of Saturn’s dense atmosphere in the northern hemisphere to see how winds at different levels may behave.
They said: ‘Past numerical and laboratory modelling efforts have succeeded in reproducing some, but not all, of the hexagon’s characteristics.
‘We present numerical simulations showing that instabilities in shallow jets can equilibrate as meanders closely resembling the observed morphology and phase speed of Saturn’s northern hexagon.
‘We also find that the winds at the bottom of the model are as important as the winds at the cloud level in matching the observed Hexagon’s characteristics, in particular its drift rate and its shape sharpness.’
The hexagon on Saturn was first discovered in 1988 in images taken by Nasa’s Voyager spacecraft as they flew past the planet in the early 1980s.
Nasa’s Cassini Spacecraft has since provided close-up colour images of the bizarre churning mass, which is twice the diameter of the Earth.
Thermal images revealed that it reached up to 60 miles (97 km) down into Saturn’s atmosphere.
Scientists have been baffled by the strange hexagonal shape encircling Saturn’s north pole (pictured) for almost 30 years, but the Cassini spacecraft revealed it extended deep into the planet’s atmosphere
Cassini provided scientists with the first close-up views of the huge storm at the north pole of Saturn and allowed them to see the planet in its true colours (pictured)
Other images revealed the points of the hexagon rotate at the same speed as Saturn’s own rotation while a jet stream was found to follow its path eastwards at speeds of around 220mph (354 km/h).
However, scientists were baffled about why the shaped formed because it did not appear to be influenced by seasons, and there were many explanations put forward.
For instance water swirling on Earth can sometimes generate vortexes that have geometric shapes.
Others have suggested they are manifestations of a ‘Rossby Wave’ rooted deep in the planet’s atmosphere that propagates vertically as the jet stream makes its way around the pole.
However, the new findings have suggested the winds beneath the jet stream are responsible for jostling this air current into its geometric shape.
This helps to explain why the hexagon is not influenced by seasonal changes, said the researchers.
It is hoped that by studying the movement of the hexagon it may be possible to understand more about the winds that are hidden beneath the stormy clouds in the gas giant’s upper atmosphere.
Speaking to Space.com, Professor Morales-Juberías said: ‘With a very simple model, we have been able to match many of the observed properties of the hexagon.’
Scientists have put forward many theories for what might be causing the vortex to take a hexagonal shape, but the new findings may help researchers understand what is going on beneath Saturn’s dense outer clouds