Has the mystery of Saturn's 20,000 mile wide hexagonal storm been solved? Researchers believe it could be controlled by a giant jet stream
- Storm on Saturn's north pole rages with winds of 200mph
- Largest wind system is 2,200 miles wide - this is twice the size of largest hurricane ever recorded on planet Earth
- Discovery has also led astronomers to calculate how often Saturn rotates for the first time
The bizarre six-sided storm churning Saturn’s north pole has flummoxed astronomers ever since it was first spotted thirty years ago.
Now, astronomers believe they may have solved one of its biggest mysteries by working out how it operates - and discovering the rotation period of Saturn in the process.
The giant storm operates rather like the jet stream on Earth they say - explaining why it never appears to move.
Scroll down for video and animations...
The animation above shows a view from directly over Saturn's north pole, keeping up with the rotation of the planet so that all the motion seen on the screen is the motion of the storms inside the hexagon.
SATURN'S HEXAGONAL VORTEX
The mysterious six-sided hexagon on Saturn’s North Pole has long captivated astronomers is thought to be is nearly 20,000 miles (30,000 kilometers).
The hexagon is made of a band of
upper-atmospheric winds which creates its six-sided shape.
A polar cyclone can be seen at its centre.
First seen by Voyagers 1 and 2 over 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 330 mph (150 metres per second).
The unusual structure with a hexagonal shape surrounding Saturn's north pole was spotted on the planet for the first time thirty years ago.
The hexagon is a wavy jet stream of 200 mph winds and spans 20,000 miles (30,000 kilometers) across - more than twice the diameter of Earth.
Nothing similar with such a regular geometry had ever been seen on any planet in the Solar System.
The Planetary Sciences Group has now been able to study and measure the phenomenon and, establish its rotation period, and that of Saturn - the only planet in the Solar System whose rotation time remains unknown.
Researchers found seasonal variations do not affect the hexagon and its jet stream at all, so concluded both are part of an extensive wave, deeply rooted in Saturn's atmosphere.
The UPV/EHU researchers suggest that the hexagon and its stream are the manifestation of a 'Rossby wave' similar to those that form in the mid-latitudes of the earth.
On our planet the jet stream meanders from west to east and brings, associated with it, the system of areas of low pressure and anticyclones which we have been seeing regularly on weather maps.
On Saturn, a hydrogen gas planet, ten times the size of the Earth, cold in its upper clouds, without a solid surface, and with an atmosphere as deep as that of an ocean, 'the hexagonal wavy motion of the jet stream is expected to be propagated vertically and reveal to us aspects of the planet’s hidden atmosphere,' said Agustín Sánchez-Lavega, Head of the Planetary Sciences research group.
Saturn's storm in action: Scientists have announced a breakthrough in understand how the storm is created
'The movement of the hexagon could therefore be linked to the depths of Saturn, and the rotation period of this structure, which, as we have been able to ascertain, is 10 hours, 39 minutes and 23 seconds, could be that of the planet itself,' he added.
Saturn is the only planet in the Solar System whose rotation period is not yet known.
Due to the tilt of approximately 27º of the planet Saturn, its polar atmosphere undergoes intense seasonable variations with long polar nights lasting over seven years, followed by a long period of 23 years of variable illumination.
In 1980 and 1981 NASA's Voyager 1 and 2 space probes passed for the first time over the planet Saturn, located 1,500 million km from the Sun.
Among their numerous discoveries they observed a strange, hexagon-shaped structure in the planet’s uppermost clouds surrounding its north pole.
The new analysis allowed astronomers to track the hexagonal storm for the first time to see how it rotated, and work out how it was formed
The hexagon remained virtually static, and images captured by the Voyager probes found that the clouds were moving rapidly inside the hexagon in an enclosed jet stream and were being dragged by winds travelling at over 400 km/h.
Thirty years later –the equivalent of one Saturn year, in other words, the time the planet takes to go all the way around the Sun– and over more than six consecutive years, researchers in the UPV/EHU’s Planetary Sciences Group, in collaboration with astronomers from various countries, were able to observe Saturn's northern polar region in detail once again and confirmed that the hexagon continued in place.
After measuring the positions of the hexagon vertices with great precision, they determined that its movement remains extremely stable, and on the basis of the cloud movements, that the jet stream inside it remains unchanged.
It comes just months after footage captured by the Cassini spacecraft using colour filters, showed researchers a complete view of the top of Saturn for the first time.
‘A hurricane on Earth typically lasts a week, but this has been here for decades - and who knows - maybe centuries,’ said Andrew Ingersoll, at the California Institute of Technology in Pasadena.
This animation above shows a view from directly over the north pole, keeping up with the rotation of the planet so that all the motion seen on the screen is the motion of the storms inside the hexagon.
This older, colour composite image - showing false shades - has been created from raw images taken by Cassini from a distance of 379,268 miles away
Weather patterns on Earth are interrupted when they encounter friction from land forms.
Scientists suspect the stability of the hexagon has something to do with the lack of solid land forms on Saturn, which is essentially a giant ball of gas.
Better views of the hexagon are available now because the sun began to illuminate its interior in late 2012.
Cassini captured images of the hexagon over a 10-hour time span with high-resolution cameras, giving scientists a good look at the motion of cloud structures within.
Scientists saw the storm around the pole, as well as small vortices rotating in the opposite direction of the hexagon.
Some of the vortices are swept along with the jet stream as if on a racetrack.
The largest of these vortices spans about 2,200 miles (3,500 km), or about twice the size of the largest hurricane recorded on Earth.
The footage captured by the Cassini spacecraft is the first of its kind, using colour filters, to show a complete view of the top of Saturn
Scientists analysed these images in false colour, a rendering method that made it easier to distinguish differences among the types of particles suspended in the atmosphere inside and outside the hexagon.
‘Inside the hexagon, there are fewer large haze particles and a concentration of small haze particles, while outside the hexagon, the opposite is true,’ said Kunio Sayanagi, a Cassini imaging team associate at Hampton University in Virginia.
‘The hexagonal jet stream is acting like a barrier, which results in something like Earth's Antarctic ozone hole.’
The Antarctic ozone hole forms within a region enclosed by a jet stream with similarities to the hexagon.
Wintertime conditions enable ozone-destroying chemical processes to occur and the jet stream prevents a resupply of ozone from the outside.
At Saturn, large aerosols cannot cross into the hexagonal jet stream from outside and large aerosol particles are created when sunlight shines on the atmosphere.
Only recently, with the start of Saturn's northern spring in August 2009, did sunlight begin bathing the planet's northern hemisphere.
‘As we approach Saturn's summer solstice in 2017, lighting conditions over its north pole will improve, and we are excited to track the changes that occur both inside and outside the hexagon boundary,’ said Scott Edgington, Cassini deputy project scientist.
The comments below have not been moderated.
The views expressed in the contents above are those of our users and do not necessarily reflect the views of MailOnline.
We are no longer accepting comments on this article.