APOD: Saturns Hexagon and Rings (2013 Feb 20)

[APOD Robot]

Saturns Hexagon and Rings

Explanation: Why would clouds form a hexagon on Saturn? Nobody is sure. Originally discovered during the Voyager flybys of Saturn in the 1980s, nobody has ever seen anything like it anywhere else in the Solar System. If Saturn's South Pole wasn't strange enough with its rotating vortex, Saturn's North Pole might be considered even stranger. The bizarre cloud pattern is shown above in great detail by a recent image taken by the Saturn-orbiting Cassini spacecraft. This and similar images show the stability of the hexagon even 20+ years after Voyager. Movies of Saturn's North Pole show the cloud structure maintaining its hexagonal structure while rotating. Unlike individual clouds appearing like a hexagon on Earth, the Saturn cloud pattern appears to have six well defined sides of nearly equal length. Four Earths could fit inside the hexagon. Imaged from the side, the dark shadow of the Jovian planet is seen eclipsing part of its grand system of rings, partly visible on the upper right.

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[ta152h0]

Maybe this could be a final destination for Cassini ......

[lakeside]

I like my crackpot theory that the hexagon is the cloud top manifestation of the largest ice crystal reef in the solar system.

JW

[walfy]

I'm surprised the APOD writers didn't even know that very excellent science was done in trying to figure out this strange structure. Here's your answer: http://www.planetary.org/blogs/emily-la ... /2471.html

[bystander]

http://asterisk.apod.com/viewtopic.php?t=30663
http://asterisk.apod.com/viewtopic.php?t=30276

[flabbergasted man]

Let's ask the bees, why a hexagon is so stable. c

[Indigo_Sunrise]

Very intriguing image!
One question: why does the link in this sentence (from the description; emphasis added):

If Saturn's South Pole wasn't strange enough with its rotating vortex,

take the user to an APOD that features Saturn's North Pole? Or is the link just an extremely close up view of the hexagon?


(<-- appropriate!)

[Boomer12k]

Always a mysterious picture. What an awesome view.

:---[===] *

[Boomer12k]

Let's ask the bees, why a hexagon is so stable. c

Interviewer: "Miss Bee, Why is a hexagon so stable?"

Miss Bee, "Because it has 6 sides, silly....".


Works for me. I wonder if in Bee evolution, they had failures with 3, 4, and 5 sides...hmmmm....maybe it is the right shape for the VOLUME for the area, and length of the comb....and six sides accommodates that best. Maybe the honey goes in better and comes out easier..... Maybe it has to do with having 6 legs....ohhhh, this could get very deep....

:---[===] *

[delgado]

I have seen this beautiful image of the Saturn hexagon. In the explanation it is said that the jovian plane eclipses the Saturn rings. I think his a mistake: jovian planet is Jupiter, isn't it? Can 'jovian' be used also for Saturn? Thanks

[BDanielMayfield]

I like my crackpot theory that the hexagon is the cloud top manifestation of the largest ice crystal reef in the solar system.

JW

OR, Crackpot theory No. 2: Saturn isn’t really a planet at all. It’s a humongous bloated flying saucer, and the proof is the giant docking port at the north pole.

I'm surprised the APOD writers didn't even know that very excellent science was done in trying to figure out this strange structure. Here's your answer: http://www.planetary.org/blogs/emily-la ... /2471.html

That is an excellent link walfy. But, as the truth always does, it shoots down all crackpot theories.

[MargaritaMc]

I have seen this beautiful image of the Saturn hexagon. In the explanation it is said that the jovian plane eclipses the Saturn rings. I think his a mistake: jovian planet is Jupiter, isn't it? Can 'jovian' be used also for Saturn? Thanks

The quick answer is, "Yes."

http://en.m.wikipedia.org/wiki/Gas_giant

A gas giant (sometimes also known as a jovian planet after the planet Jupiter, or giant planet) is a large planet that is not primarily composed of rock or other solid matter.

Margarita

[MargaritaMc]

I'm surprised the APOD writers didn't even know that very excellent science was done in trying to figure out this strange structure. Here's your answer: http://www.planetary.org/blogs/emily-la ... /2471.html

This is from the link that walfy posted

image courtesy of Ana Aguiar

Creating Saturn's hexagon in the laboratory

This is a top-down view of a laboratory tank in an experiment designed to reproduce the wind conditions near Saturn's north pole. The whole cylindrical tank is 60 centimeters wide. Its lid and base are split into two concentric sections, with the inner circle being 30 centimeters in diameter. The inner and outer circles are rotated at different rates, which sets up an instability at their boundary, producing a standing wave; the number of waves it takes to encircle the "pole" depends on various experimental parameters, including the rotation speed. In this particular case, the wavenumber is 6, producing a hexagon. Dye has been injected into the tank to make the form of the turbulent flow visible. Eddies are produced outside the wave.

As has previously been noted, the whole blog post is extremely worth studying.

Margarita

[rstevenson]

Just a few days ago I watched a recent episode of PBS's excellent Nova program, Earth From Space. Part way through it, in a section about weather systems around Antarctica, they showed a time-lapse video of low-pressure systems whirling around the continent over the space of motnhs. A sometimes hexagonal pattern appeared in a kind of pulsating way, not always there, not always hexagonal, but definitely a pattern. It seems complex systems, given the right conditions, naturally create geometric shapes, if not always stable ones.

Rob

[Chris Peterson]

It seems complex systems, given the right conditions, naturally create geometric shapes, if not always stable ones.

It is worth noting that outside of carefully contrived setups, no complex system (which, in fact, includes systems that might seem incredibly simple to us) are stable. It's always a question of how long some sort of metastability can be maintained.

[ChrisA]

Very intriguing image!
One question: why does the link in this sentence (from the description; emphasis added):

If Saturn's South Pole wasn't strange enough with its rotating vortex,

take the user to an APOD that features Saturn's North Pole? Or is the link just an extremely close up view of the hexagon?

Yeah, this confused me, too. To be clear, Saturn has vortices at both poles. But AFAIK, only the North Pole has the hexagon. APOD just mislabeled their link to the 121204 entry (which was showing the vortex at the North Pole, not the South Pole).

[neufer]

Just a few days ago I watched a recent episode of PBS's excellent Nova program, Earth From Space. Part way through it, in a section about weather systems around Antarctica, they showed a time-lapse video of low-pressure systems whirling around the continent over the space of months. A sometimes hexagonal pattern appeared in a kind of pulsating way, not always there, not always hexagonal, but definitely a pattern. It seems complex systems, given the right conditions, naturally create geometric shapes, if not always stable ones.

It is worth noting that outside of carefully contrived setups, no complex system (which, in fact, includes systems that might seem incredibly simple to us) are stable. It's always a question of how long some sort of metastability can be maintained.

I never meet a stable I didn't like.

Atmospheric RO(ss)B(y) waves were "discovered" by a Swedish American to help explain why Nova Scotia is colder than Sweden:

[img3="Meanders of the northern hemisphere's jet stream developing (a, b) and finally detaching a "drop" of cold air (c). Orange: warmer masses of air; white: jet stream. [If the Earth rotated in just
10.6 hours the polygonal pattern would be MUCH more stable]"]http://upload.wikimedia.org/wikipedia/c ... aves_N.gif[/img3]

<<Atmospheric Rossby waves are giant meanders in high-altitude winds that are a major influence on weather.

Atmospheric Rossby waves emerge due to shear in rotating fluids, so that the Coriolis force changes along the sheared coordinate. In planetary atmospheres, they are due to the variation in the Coriolis effect with latitude. The waves were first identified in the Earth's atmosphere in 1939 by Carl-Gustaf Arvid Rossby who went on to explain their motion.

One can identify a Rossby wave in that its phase velocity (that of the wave crests) always has a westward component. However, the wave's group velocity (associated with the energy flux) can be in any direction. In general, shorter waves have an eastward group velocity and long waves a westward group velocity.

The terms "barotropic" and "baroclinic" Rossby waves are used to distinguish their vertical structure:

• 1) Barotropic Rossby waves do not vary in the vertical, and have the fastest propagation speeds.
  2) The baroclinic wave modes are slower, with speeds of only a few centimetres per second or less.

Most work on Rossby waves has been done on those in Earth's atmosphere. Rossby waves in the Earth's atmosphere are easy to observe as (usually 4-6) large-scale meanders of the jet stream. When these deviations become very pronounced, they detach the masses of cold, or warm, air that become cyclones and anticyclones and are responsible for day-to-day weather patterns at mid-latitudes. Rossby waves may be partly responsible for the fact that eastern continental edges, such as the Northeast United States and Eastern Canada, are colder than Europe at the same latitudes.>>

[neufer]

[b][color=#0000FF]Saturn's north pole vortex, as viewed at 750 nm through a polarizer[/color][/b]

---

<<Hex signs are a form of Pennsylvania Dutch folk art, related to fraktur, found in the Fancy Dutch tradition in Pennsylvania Dutch Country. Barn paintings, usually in the form of "octagon or hexagon stars in circles," grew out of the fraktur and folk art traditions about 1850 when barns first started to be painted in the area. Prior to the 1830s, the cost of paint meant that most barns were unpainted. The geometric patterns of quilts can be seen in the patterns of many hex signs.

The term hex with occult connotations may derive from the Pennsylvanian German word "hex" (German "Hexe", Dutch "Heks"), meaning "witch." However the term "hex sign" was not used until the 20th Century, after 1924 when Wallace Nutting's book Pennsylvania Beautiful was published. Before this time many Pennsylvania German farmers simply called the signs "blumme" or "schtanne" (meaning flowers or stars). However one farmer used the term "Hexefoos" in his description.

Some view the designs as decorative symbols of ethnic identification, possibly originating in reaction to 19th century attempts made by the government to suppress the Pennsylvania German language. Anabaptist sects (like the Amish and Mennonites) in the region have a negative view of hex signs. It is not surprising that hex signs are rarely, and perhaps never, seen on an Amish or Mennonite household or farm.>>

[delgado]

I have seen this beautiful image of the Saturn hexagon. In the explanation it is said that the jovian plane eclipses the Saturn rings. I think his a mistake: jovian planet is Jupiter, isn't it? Can 'jovian' be used also for Saturn? Thanks

The quick answer is, "Yes."

http://en.m.wikipedia.org/wiki/Gas_giant

A gas giant (sometimes also known as a jovian planet after the planet Jupiter, or giant planet) is a large planet that is not primarily composed of rock or other solid matter.

Margarita

Thanks!. I did not know. In this case, jovian should not be with capital, "Jovian", as it is, but rather as "jovian" , since it is not a proper name but an adjectiv. Thanks again!

[ta152h0]

Bucky balls. I remember now

[RJN]

I'm surprised the APOD writers didn't even know that very excellent science was done in trying to figure out this strange structure. Here's your answer: http://www.planetary.org/blogs/emily-la ... /2471.html

Yes that's a good link and discussion that I did indeed miss. Thanks for pointing it out! I have now linked to it under "six well defined sides".
- RJN

[Chris Peterson]

I have seen this beautiful image of the Saturn hexagon. In the explanation it is said that the jovian plane eclipses the Saturn rings. I think his a mistake: jovian planet is Jupiter, isn't it? Can 'jovian' be used also for Saturn? Thanks

"Jovian" can refer specifically to Jupiter, or to the class of planets of which Jupiter is the exemplar. In the same way, "terrestrial" can refer specifically to Earth (Terra), or to the class of rocky planets for which Earth is the exemplar.

[Chris Peterson]

In this case, jovian should not be with capital, "Jovian", as it is, but rather as "jovian" , since it is not a proper name but an adjectiv.

In English, it is usual, although not universal, to retain the capital for adjectives derived from proper nouns. The several dictionaries I checked all list "Jovian" only as a capitalized adjective. That said, however, I think this is largely about style, and not any absolute rules. I'd consider either usage equally acceptable.

In my own usage, I'd probably be inclined to use "jovian" in reference to the class of jovian planets, and "Jovian" when referring to Jovian winds [on Jupiter].

[neufer]

Click to play embedded YouTube video.

In this case, jovian should not be with capital, "Jovian", as it is, but rather as "jovian" , since it is not a proper name but an adjectiv.

In English, it is usual, although not universal, to retain the capital for adjectives derived from proper nouns. The several dictionaries I checked all list "Jovian" only as a capitalized adjective. That said, however, I think this is largely about style, and not any absolute rules. I'd consider either usage equally acceptable. In my own usage, I'd probably be inclined to use "jovian" in reference to the class of jovian planets, and "Jovian" when referring to Jovian winds [on Jupiter].

[JoeyZola]

Here's a curve-ball for everyone involved... Recently on a TV programme about global weather they ran a three-year sequence of Antarctica and surroundings. During the sequence, several times a perfect hexagon appeared in the wind-patterns over the continent, around the South Pole. I'd love to see someone with the resources research this and see how often that formation occurs, and perhaps in which seasons. Studying another planet's weather systems allows us to learn about our own. In this case a large planet with a large semi-permanent weather system has show us what happens on a smaller, briefer scale on our own Planet.