The Mystery Hexagon on Saturn
Hexagonal Wave Pattern Around the North Polar Vortex



The Mystery Hexagon on Saturn
Hexagonal Wave Pattern Around the North Polar Vortex

Saturn holds a secret, a mysterious Hexagon over the north pole.
The pattern's origin is a matter of much speculation. Most astronomers seem to think it was caused by some standing-wave pattern in the atmosphere; but the hexagon might be a novel aurora. Polygonal shapes have been replicated in spinning buckets of fluid in a laboratory.


Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn, along with Jupiter, Uranus and Neptune, is classified as a gas giant.

Together, these four planets are sometimes referred to as the Jovian, meaning "Jupiter-like", planets. Saturn is named after the Roman god Saturn, equated to the Greek Cronus (the Titan father of Zeus) the Babylonian Ninurta and to the Hindu Shani. Saturn's symbol represents the god's sickle.


From 2004 to November 2nd, 2009, the Cassini-Huygens spacecraft has discovered and confirmed 8 new satellites orbiting Saturn.

The planet Saturn is composed of hydrogen, with small proportions of helium and trace elements. The interior consists of a small core of rock and ice, surrounded by a thick layer of metallic hydrogen and a gaseous outer layer.

The outer atmosphere is generally bland in appearance, although long-lived features can appear.

Wind speeds on Saturn can reach 1,800 km/h, significantly faster than those on Jupiter. Saturn has a planetary magnetic field intermediate in strength between that of Earth and the more powerful field around Jupiter.


A persisting hexagonal wave pattern around the north polar vortex in the atmosphere at about 78°N was first noted in the Voyager images.

Unlike the north pole, HST imaging of the south polar region indicates the presence of a jet stream, but no strong polar vortex nor any hexagonal standing wave.

However, NASA reported in November 2006 that the Cassini spacecraft observed a 'hurricane-like' storm locked to the south pole that had a clearly defined eyewall.

This observation is particularly notable because eyewall clouds had not previously been seen on any planet other than Earth (including a failure to observe an eyewall in the Great Red Spot of Jupiter by the Galileo spacecraft).

The straight sides of the northern polar hexagon are each about 13,800 km long.

The entire structure rotates with a period of 10h 39 m 24s, the same period as that of the planet's radio emissions, which is assumed to be equal to the period of rotation of Saturn's interior.


The hexagonal feature does not shift in longitude like the other clouds in the visible atmosphere. The pattern's origin is a matter of much speculation.

Most astronomers seem to think it was caused by some standing-wave pattern in the atmosphere; but the hexagon might be a novel aurora.

Polygonal shapes have been replicated in spinning buckets of fluid in a laboratory.

 
A persisting hexagonal wave pattern around the north polar vortex in the atmosphere was first noted in the Voyager images.

The pattern's origin is a matter of much speculation. Most astronomers seem to think it was caused by some standing-wave pattern in the atmosphere; but the hexagon might be a novel aurora.

Polygonal shapes have been replicated in spinning buckets of fluid in a laboratory.





Saturn, along with Jupiter, Uranus and Neptune, is classified as a gas giant. Together, these four planets are sometimes referred to as the Jovian, meaning "Jupiter-like", planets.

Saturn has an average radius about 9 times larger than the Earth's. While only 1/8 the average density of Earth, due to its larger volume, Saturn's mass is just over 95 times greater than Earth's.


Because of Saturn's large mass and resulting gravitation, the conditions produced on Saturn are extreme if compared to Earth.

The interior of Saturn is probably composed of a core of iron, nickel, silicon and oxygen compounds, surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium and finally, an outer gaseous layer.

Electrical current within the metallic-hydrogen layer is thought to give rise to Saturn's planetary magnetic field, which is slightly weaker than Earth's magnetic field and approximately one-twentieth the strength of the field around Jupiter.

The outer atmosphere is generally bland in appearance, although long-lived features can appear. Wind speeds on Saturn can reach 1,800 km/h, significantly faster than those on Jupiter.

Saturn has nine rings, consisting mostly of ice particles with a smaller amount of rocky debris and dust. Sixty-two known moons orbit the planet; fifty-three are officially named. This is not counting hundreds of "moonlets" within the rings.

Titan, Saturn's largest and the Solar System's second largest moon (after Jupiter's Ganymede), is larger than the planet Mercury and is the only moon in the Solar System to possess a significant atmosphere.

Due to a combination of its lower density, rapid rotation and fluid state, Saturn is an oblate spheroid; that is, it is flattened at the poles and bulges at the equator. Its equatorial and polar radii differ by almost 10%—60,268 km versus 54,364 km.

The other gas planets are also oblate, but to a lesser extent. Saturn is the only planet of the Solar System that is less dense than water. Although Saturn's core is considerably denser than water, the average specific density of the planet is 0.69 g/cm³ due to the gaseous atmosphere.

Saturn is only 95 Earth masses, compared to Jupiter, which is 318 times the mass of the Earth but only about 20% larger than Saturn.

Though there is no direct information about Saturn's internal structure, it is thought that its interior is similar to that of Jupiter, having a small rocky core surrounded mostly by hydrogen and helium.

The rocky core is similar in composition to the Earth, but more dense. This is surrounded by a thicker liquid metallic hydrogen layer, followed by a liquid hydrogen/helium layer and a gaseous atmosphere in the outermost 1000 km. Traces of various volatiles are also present.

The core region is estimated to be about 9–22 times the mass of the Earth. Saturn has a very hot interior, reaching 11,700 °C at the core and it radiates 2.5 times more energy into space than it receives from the Sun. Most of this extra energy is generated by the Kelvin-Helmholtz mechanism (slow gravitational compression), but this alone may not be sufficient to explain Saturn's heat production.

It is proposed that an additional mechanism might be at play whereby Saturn generates some of its heat through the "raining out" of droplets of helium deep in its interior, thus releasing heat by friction as they fall down through the lighter hydrogen.



Saturn's Strange Hexagon Simulated in Laboratory


Physicists Ana Claudia Barbosa Aguiar and
Peter Read of the University of Oxford in the United Kingdom performed the experiment depicted in this video.

Using a 30-liter cylinder of water placed on a slowly rotating table they created an artificial "jet stream" by employing a much smaller and much faster rotating ring inside the main cylinder.


By introducing fluorescent dye into the artificial "jet stream" they discovered that stable eddies formed and became stronger over time eventually forming stable regular polygonal shapes with each eddy located at a vertex.

Also, in varying the rate of rotation of the large cylinder with respect to the small ring, they discovered that the larger the relative difference in rotation rates the less sides the resulting polygon had.

The experimenters postulate that a similar process is occurring on Saturn where the cylinder would be analogous to Saturn's rotation and the "jet stream" would be analogous to an actual jet stream with an angular velocity greater than that of the planet's rotation.

It is still unknown what exactly would generate such a jet stream and especially one at just the right angular velocity to produce a hexagon.