New Cassini Images Show Saturn's Hexagon

The hexagon structure on Saturn, which is most likely formed by jet streams at the gas giant's north pole.
Image credits: NASA / JPL / Space Science Institute

Cassini Images Saturn's Hexagon

In the early 1980s, as the Voyager probe was passing by Saturn, it noticed one of the most peculiar space structures that experts had ever seen. The formation, which is roughly hexagon-shaped, is still a mystery for astronomers. Theories as to its origins abound, but none of them has managed to make itself established and widely accepted in the international scientific community. The hexagon encircles Saturn with a diameter roughly equal to two Earths, Space reports. The Cassini spacecraft, in orbit around the gas giant since 2004, has recently been able to photograph the structure again.

Most likely, scientists seem to believe, the structure is a cloud-generated formation, which is able to endure for many years. The jet stream that is thought to be responsible for the creation of the hexagonal clouds keeps flowing at the planet's north pole, the experts say. It is estimated at this point that the jets are capable of slamming into the clouds at speeds exceeding 220 miles per hour (100 meters per second). The clouds were imaged for the last time more than 30 years ago, as the last spring began on the surface of Saturn.

“The longevity of the hexagon makes this something special, given that weather on Earth lasts on the order of weeks. It's a mystery on par with the strange weather conditions that give rise to the long-lived Great Red Spot of Jupiter,” California Institute of Technology (Caltech) Cassini imaging team associate Kunio Sayanagi, who has been a part of the new investigation, says. He adds that, 15 years after the original Voyager photos were captured, the Saturnine north pole was enveloped in darkness.

Unlike its predecessor, the new space probe benefits from a better viewing angle, which allows it to position itself better for observing the Hexagon. It also carries massively improved scientific payloads, including high-resolution cameras and spectrometers, which allow it to collect as much information as possible about its targets, while using limited means. The new photos were taken in infrared, and reveal that the cloudy structure is still in place, and also very extended within the gas giant's atmosphere.

“Now that we can see undulations and circular features instead of blobs in the hexagon, we can start trying to solve some of the unanswered questions about one of the most bizarre things we've ever seen in the solar system. Solving these unanswered questions about the hexagon will help us answer basic questions about weather that we're still asking about our own planet,” NASA Jet Propulsion Laboratory (JPL) atmospheric scientist Kevin Baines concludes. JPL is managed by Caltech, in Pasadena.

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Into the Milky Way
OPPL unveils Milky Way images, hosts talk on Saturn mission

Visitors to the Orland Park Public Library traveled to the Milky Way Galaxy and Saturn on Wednesday, Nov. 18, a the library unveiled mural-sized images of the Milky Way Galaxy from NASA's Great Observatories.

The image unveiling was conducted by the library as way to celebrate the International Year of Astronomy 2009, which celebrates the 400th anniversary of Galileo using a telescope to view the sky. The murals will be permanently on display in the Youth Services Department of the library in mid-December. The Orland library is one of 10 in Illinois, and one of 152 libraries in the country, to receive the images.

As OPPL Library Director Mary Weimar uncovered the images, the audience of more than 40 people applauded.

"We've been very blessed in the last five years to get grants to show past and present events," said OPPL Library Director Mary Weimar. "People see the Milky Way Galaxy on the news with the discoveries, and to know that we have the opportunity to bring them closer to Orland patrons is wonderful. It's very exciting.

"We like to be on the cutting edge of information."

The images feature views from all three of NASA's Great Observatories — near-infrared light from the Hubble Space Telescope, infrared light from the Spitzer Space Telescope and the X-ray light observed by Chandra X-ray Observatory.

To also commemorate the unveiling, John Vittallo, Solar System Ambassador for the Jet Propulsion Laboratory for CalTech and NASA, led a discussion about the Cassini/Huygens Mission to Saturn.

Vittallo said that the mission, which began on Oct. 15, 1997, was a 7-year journey, with the space craft traveling at speeds of 42,000 mph to reach Saturn on July 1, 2004.

"With 61 moons, it's a very complex place," he said.

Vittallo said that the mission gave NASA much knowledge about Saturn. The mission included a landing on Titan, one of Saturn's moons, which taught scientists that the atmosphere was mostly nitrogen, with a vast expanse of dunes and a surface similar to wet sand.

"A day on Saturn lasts about 10 hours," he said. "The planet is mostly hydrogen and is sunny."

Vittallo played an audio clip of what the radio waves emitting from Saturn sounds like.

"It puts you in the mood to rent 'Forbidden Planet,'" he said jokingly.

Vittallo said that what this mission discovered at the poles of the planet was something scientists had not expected.

"Measuring 5,000 miles wide and 45 miles deep is a persistent hurricane at the south pole," he said. "It was totally unexpected."

At the north pole is a hexagon cloud.

"There is a persistent hexagon cloud feature that is about 15,000 miles across and it rotates at the same speed as Saturn," Vittallo said. "I haven't heard too many explanations as to why it exists."

Close-up photos of Saturn's numerous rings were also shown.

"I don't want to discredit [astronomer Giovanni] Cassini or [astronomer Chistiaan] Huygens, but they couldn't predict that beauty and kind of detail," Vittallo said, as he revealed an image of the creamy white and light gray rings.

Images of Saturn's moons, including Mimas and Enceladus, were also shown. Enceladus, Vittallo said, is the brightest object in the solar system.

"It's a near-perfect reflector and part of the reason is because it's surface is like freshly fallen snow," he said. "With the lines, it shows evidence that there is something going on.

"It's likely a salt water ocean — a sort of cosmic Old Faithful that spews out water vapor. There is currently an extended mission to fly through the plumes to sample them and see what's down there."

For more information about about NASA's celebration of the International Year of Astronomy, visit astronomy2009.nasa.gov.

For more information about the mission to Saturn, visit www.saturn.jpl.nasa.gov.

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