The Storm Around Saturn’s North Pole

Saturn_hurricane1The Cassini spacecraft relayed to Earth thist close-up, visible-light views of a monster hurricane swirling around Saturn’s north pole. It’s 2,000 km wide, 20 times larger than the average hurricane eye on Earth. The clouds at the outer edge of the hurricane are moving at 150 meters per second as the storm swirls inside a large, six-sided weather pattern known as the hexagon. This false-color image highlights the storm at Saturn’s north pole.

Saturn_hurricane3A natural color image is at left.

Hurricanes on Earth feed off warm ocean water, but there is no body of water on Saturn. Learning how these Saturnian storms use water vapor might tell scientists more about how terrestrial hurricanes are generated and sustained. Both terrestrial hurricanes and Saturn’s north polar vortex have a central eye with no clouds or very low clouds. Both have high clouds forming an eye wall, other high clouds spiraling around the eye, and a counter-clockwise spin in the northern hemisphere. But the one on Saturn is much bigger than its counterparts on Earth and spins surprisingly fast. On Saturn, the wind in the eye wall blows more than four times faster than hurricane-force winds on Earth. Terrestrial hurricanes move around, but Saturn’s hurricane is parked over the planet’s north pole. On Earth, hurricanes tend to drift northward because of the forces acting on the winds as the planet rotates. Saturn’s does not drift; it’s already as far north as it can be.

Saturn_hurricane2Scientists believe the massive storm has been churning for years. When Cassini arrived in the Saturn system in 2004, Saturn’s north pole was in winter darkness. Cassini‘s composite infrared spectrometer and visual and infrared mapping spectrometer detected the great vortex, but a visible-light image had to wait for the equinox in 2009 when sunlight begin falling on the higher latitudes of Saturn’s northern hemisphere.

Image Credits: NASA

Smog on Saturn

north-poleThese two natural color images taken by the Cassini spacecraft show how Saturn’s north polar region has changed between 2012 and 2016. The color change is thought to be an effect of Saturn’s seasons. It’s believed that the change from a bluish color to a more golden hue is caused by the increased production of smog in the atmosphere as the north pole approached the summer solstice due in May, 2017.

The hexagon, Saturn’s six-sided jetstream, seems to act as a barrier preventing haze particles produced outside it from entering. If that’s the case, the polar atmosphere becomes clear of aerosols produced by photochemical reactions, reactions caused by sunlight, during the winter darkness. After Saturn’s northern spring equinox, the north pole polar is in continuous sunshine, and smog aerosols can be produced inside the hexagon, making the polar atmosphere appear hazy.

Image Credit: NASA

Saturn’s North Pole

north-poleThese two natural color images taken by the Cassini spacecraft show how Saturn’s north polar region has changed between 2012 and 2016. The color change is thought to be an effect of Saturn’s seasons. It’s suggested that the change from a bluish color to a more golden hue is due to the increased production of smog in the atmosphere as the north pole approaches summer solstice in May, 2017.

The hexagon, Saturn’s six-sided jetstream, may act as a barrier preventing haze particles produced outside it from entering. If that’s the case, the polar atmosphere could have become clear of aerosols produced by photochemical reactions, reactions caused by sunlight, during the winter. After Saturn’s equinox in August, 2009, the north pole polar has been in continuous sunshine, and smog aerosols are being produced inside the hexagon, making the polar atmosphere appear hazy.

Image Credit: NASA

Saturn’s Hexagon

hexagonThis animation was assembled using images from the Cassini spacecraft and is the highest-resolution view of the unique six-sided jet stream at Saturn’s north pole known as “The Hexagon.” It shows a complete view from the north pole down to about 70 degrees north latitude. The images have been rotated to account for the spin of the planet so that the point of view is as if we were in space above Saturn and rotating on its axis with it.

There is a wide variety of cloud structures within The Hexagon, including a massive hurricane tightly centered on the north pole, with an eye about 50 times larger than the average hurricane eye on Earth. There are numerous small vortices which show up as reddish ovals. Some of these vortices spin clockwise while The Hexagon and central hurricane spin counterclockwise. Some are swept along with the jet stream of The Hexagon. The biggest of these vortices, seen near the lower right, spans about 3,500 kilometers, roughly twice the size of the largest hurricane on Earth.

This is a false color movie in which different wavelengths of light from ultraviolet to visible to infrared have been assigned colors to enhance the contrast between the types of atmospheric particles inside and outside The Hexagon. On the inside there are fewer large haze particles and a concentration of small haze particles. Outside The Hexagon, the reverse is true. The jet stream that makes up the structure seems to act like a barrier, which results in something like the “ozone hole” in the Antarctic on Earth.

The Hexagon is an amazingly stable structure. Storms on Earth die out because of friction with the solid surface of the planet. Saturn is a gas giant. As summer returns to the its northern hemisphere, we will be watching for changes in The Hexagon.

Image Credit: NASA

Hurricane on Saturn

Saturn_hurricane1The Cassini spacecraft has relayed to Earth the first close-up, visible-light views of a monster hurricane swirling around Saturn’s north pole. It’s 2,000 km wide, 20 times larger than the average hurricane eye on Earth. The clouds at the outer edge of the hurricane are moving at 150 meters per second as the storm swirls inside a large, mysterious, six-sided weather pattern known as the hexagon. This false-color image highlights the storm at Saturn’s north pole.

Saturn_hurricane3A natural color image is at left.

Hurricanes on Earth feed off warm ocean water, but there is no body of water on Saturn. Learning how these Saturnian storms use water vapor might tell scientists more about how terrestrial hurricanes are generated and sustained. Both terrestrial hurricanes and Saturn’s north polar vortex have a central eye with no clouds or very low clouds. Both have high clouds forming an eye wall, other high clouds spiraling around the eye, and a counter-clockwise spin in the northern hemisphere. But the one on Saturn is much bigger than its counterparts on Earth and spins surprisingly fast. On Saturn, the wind in the eye wall blows more than four times faster than hurricane-force winds on Earth. Terrestrial hurricanes move around, but Saturn’s hurricane is parked over the planet’s north pole. On Earth, hurricanes tend to drift northward because of the forces acting on the winds as the planet rotates. Saturn’s does not drift; it’s already as far north as it can be.

Saturn_hurricane2Scientists believe the massive storm has been churning for years. When Cassini arrived in the Saturn system in 2004, Saturn’s north pole was in winter darkness. Cassini‘s composite infrared spectrometer and visual and infrared mapping spectrometer detected the great vortex, but a visible-light image had to wait for the equinox in 2009 when sunlight begin falling on the higher latitudes of Saturn’s northern hemisphere. Cassini‘s orbit had to be changed so the spacecraft could see the poles. The spacecraft changes its orbital inclination for such an observing campaign only once every few years. Because the spacecraft uses flybys of Saturn’s moon Titan to change the angle of its orbit, the inclined trajectories require careful planning years in advance to ensure sufficient fuel is available for the spacecraft to reach future planned orbits and encounters.

Image Credits: NASA