Spring Unveils Saturn's Hexagon [720p]

This movie from Cassini, made possible only as Saturn's north pole emerged from winter darkness, shows new details of a jet stream that follows a hexagon-shaped path and has long puzzled scientists.

The hexagon was hidden in darkness during the winter of Saturn's long year, a year that is equal to about 29 Earth years. But as the planet approached its August 2009 equinox and signaled the start of northern spring, the hexagon was revealed to Cassini's cameras. This is the first time the whole hexagonal shape has been mapped out in visible light by Cassini, and these images show unprecedented details of Saturn's high northern latitudes. The hexagon was originally discovered in images taken by Voyager spacecraft in the early 1980s. Since 2006, the Cassini Visual and Infrared Mapping Spectrometer (VIMS) instrument has been observing the hexagon at infrared wavelengths, but at lower spatial resolution than these visible light images.

Three large mosaics were used to create this three-frame movie. The mosaics used dozens of images and the constituent images were projected into polar projections to provide a complete view of the hexagon. The mosaics used in this movie do not show the region directly around the north pole because it had not yet fully emerged from the polar winter night. Seams between the images are visible in the third frame of the movie because the observation geometry in those images made removal of the seams difficult.

The six-sided shape remains a mystery. Scientists think the hexagon is a meandering jet stream at 77 degrees north latitude, but they don't know what controls the path the stream takes. These images also show new phenomena for scientists to decipher, such as waves that can now be seen radiating from the corners of the hexagon where the jet takes its hardest turns. These images confirm the presence of a multi-walled structure in each of the hexagon's six sides, and the structure now can be seen extending to the top of Saturn's cloud layer. The images show that the inside of the hexagon is darker than the outside. The new images also show a large spot inside the hexagon that could be related to a dark spot seen inside the hexagon in 2006 in an image taken by Cassini's VIMS instrument. An earlier Voyager mosaic showed a large spot outside the hexagon. That spot existed at least until 1991 before disappearing into the long winter polar night.

Images from Voyager and from ground-based telescopes suffered from poor viewing perspectives. In late 2006, Cassini's VIMS camera imaged the region in the thermal infrared wavelength, showing the hexagon in false color. Multiple images acquired by the VIMS instrument over a 12-day period showed that the feature is nearly stationary and is likely an unusually strong pole-encircling planetary wave that extends deep into the atmosphere. Scientists had speculated that a large vortex seen outside the hexagon during the Voyager observations exerted forces on the jet stream making it adopt a hexagonal pattern in a manner similar to how jet streams on Earth divert around high-pressure systems. However, in these new images, the vortex is notably absent while the hexagon persists almost 30 years after it was first seen.

Credit: Credit: NASA/JPL/Space Science Institute

Category:

Science & Technology

Tags:

• Saturn
• Saturn's hexagon
• Saturn's atmosphere

[FletcherHabit]

When does that probe land scheduled to arrive mid 2011  i forget exactly.. anybody know what im talking about?

[djxatlanta]

@FletcherHabit - The Huygens probe landed on Titan in January 2005 and took some incredible photos on the way down. A year or two ago I posted some movies of the landing produced by ESA compiled from the descent imagery. Pretty cool stuff. The next lander mission is the Curiosity rover to land on Mars in August 2012. Then a Russian mission will land on Phobos sometime in 2012 to collect rock samples to return to Earth.

[argodell]

Its funny how the biggest mystery in the solar system has had almost no media or documentary coverage to speak of.

[djxatlanta]

@argodell - there are plenty of interesting phenomena at Saturn and its rings and moons. Truth be told, the polar hexagon has been discussed in scientific circles for almost 30 years, but atmospheric fluid dynamics doesn't have the flashy zing in documentaries compared to the more media-friendly ice geysers on Enceladus, the Earthlike geology and weather on Titan, the two faces of Iapetus and of course those gorgeous rings!

[Shainkov]

what worries me is that nasa discovered it in the 80s, and never told us about it till now. i wonder how many things they know, but they're not telling us right now.

Think about it.

[djxatlanta]

@Shainkov - actually, yes, it was announced back in 1980 and 1981. As a kid, I followed the Voyager space program quite a bit through the 70s and 80s, and I very much remember when it was discovered. I haven't seen all the research, but it's a completely natural atmospheric effect. I've seen some videos where they simulate Jupiter's and Saturn's atmospheres with spinning circular tanks, and they can re-create Saturn's hexagon and Jupiter's Great Red Spot in the laboratory.

[LilyLava]

I blinked and missed it.

[xlucioflavio]

2 seconds?

[Regis2007]

Eu tenho uma teoria:

A atmosfera de netuno é rica em partículas matálicas. Os ventos movimentam as partículas atmosféricas assim como qualquer outra atmosfera planetária. Deveria então não haver qualquer simetria correto?

No caso de Saturno também há um forte fluxo magnético que inicia no polo que favorece a formação dessa simetria.

Para um exemplo prático vejam os vídeos de ferro-fluídos que rolam pelo Youtube, o líquido carregado de partículas metálicas formam incríveis estruturas.

[blu3m4trix]

@sgtgary66 I looked into it and that sounds about rite. Think what had me confused was NASA's wording of the picture. "in 2009 the mysterious hexagonal vortex became fully illuminated by sunlight for the first time during the Cassini's visit. Since then, Cassini has imaged the rotating hexagon in visible light enough times to create a time-lapse movie." I think i assumed they should have had a full view of the pole but i guess not. Thanks for clearing that up for me.

[sgtgary66]

@blu3m4trix I completely forgot about the fact that Saturn's orbit is so long that it only just hit equinox. Since the image is made up of weeks worth of images, the pole itself hasn't been lit yet. I imagine the visible light image that reaches the pole will be available soon, once the imager captures the dimly lit north pole.

[blu3m4trix]

@sgtgary66 Can you then explain why the infrared images of the same object are not blacked out? There are even video's/time lapse clips from the infrared camera of this exact location on saturn and nothing in censored.

[EthelRethor]

@Shainkov

The fact that NASA didn't give you a call about it doesn't mean that they are hiding it. It's even old news for scientists and people interested in science.

[sgtgary66]

@blu3m4trix it's not "censored". When an imager is near the equator of a sphere, it cannot image the polar regions (and they are extremely stretched out). This is no different than NOAA's GOES geostationary satellites that watch Earth's weather. We cannot see the poles of earth so we have a different kind of satellite (polar orbiters) to see those areas. Unfortunately, NASA doesn't have anything in a good orbit to image the entire polar region of Saturn.

[blu3m4trix]

So why is the center of the picture censored/blacked out. Nasa apparently has hundreds of photo's of this and they can't find one good one to show. The first time there are full visible light images of the hexagon and its censored. BS

[vmarb]

It makes a great game to try to push the pause button right when it forms a perfect circle, before it ends...you have to be quick though.

[thurmanrandy]

@Shainkov they know about spreading persistent contrails, and the information is easy to find from NASA, they think it will have an effect on our natural resources but they are not sure. But, no one cares. Check contrail edcuation for more info.