What is the Hexagon of Saturn?

Saturn is a beautiful planet that boasts stunning features in its atmosphere. One such feature is the hexagon in Saturn’s north pole

This hexagonal feature is made of a jet stream that moves in such a way that it forms a hexagonal shape. 

This feature has been observed for nearly 40 years and changes colors according to Saturn’s seasons.

What is it made of? Why does it change colors like that? Why did it form, and what are the forces behind it that continue to drive its persistent existence? 

While scientists don’t know the answers to all of those questions, the Cassini spacecraft that visited Saturn has taken us closer to finding the answers.

Saturn’s Hexagon feature (Source)

It is not always possible to photograph this feature because of Saturn’s orbit, seasons, and its tilt towards Earth, but we will see in this article how to make the most of it, and where you can find the best resources and pictures for references

Let’s dive in! 

When and How Was the Hexagon Discovered?

Saturn’s hexagon is the term for a pattern of cloud in the shape of a hexagon. This formation is present at Saturn’s North Pole, at ~78 degrees. The hexagon’s sides span roughly 9,000 miles (14,500 km), which makes each side bigger than Earth’s diameter. The whole area is about 18,000 miles wide (29,000 km) and 190 miles (300 km) high. 

The hexagon was first discovered by the Voyager spacecraft when it visited Saturn in 1981. It was studied a second time by the Cassini spacecraft in 2006

For a brief period of time, Cassini traveled at the same speed as Saturn, which allowed it to precisely measure the hexagon’s movement, whose rotation period was determined to be 10h 39m 24s. 

What is the Hexagon of Saturn Made Of?

The short answer is that we do not know the exact chemical composition of Saturn’s Hexagon. 

Scientists hypothesize that phosphine gas is depleted in the hexagon’s atmosphere, but that is all that we know for sure. Saturn’s atmosphere consists of 75% hydrogen, so the Hexagon itself will be dominant in hydrogen, as well as traces of other gases. 

Scientists did notice that Saturn’s hexagon changed its color from hazy golden to blue when the Cassini spacecraft observed it.

Saturn’s seasons change once every 7 Earth years (1 Saturnian year = 29 Earth years). Summers on Saturn result in increased sunlight on the poles, and scientists found evidence of aerosols that were created in Saturn’s atmosphere, giving it a golden color.

In Saturnian winters, there wasn’t as much sunlight reaching the northern poles, so the number of aerosols decreased and the hexagon returned to its original bluish state. 

How Does It Work?

Saturn’s Hexagon is created because of deep thermal convection. This occurs when heat travels from one place to another within the planet, leaving jet streams in its wake

The jet streams in Saturn’s north pole forming a hexagonal shape (Source)

These jet streams are many in number, and when they mix at the top of Saturn’s atmosphere, they form different shapes. 

This is why we notice many such jet streams throughout the year, but the Hexagon is the only formation that has remained consistent.

It is associated with an eastward zonal jet and rotates at the same time as Saturn itself. The formation is about 200 miles deep into Saturn’s atmosphere. 

It was first discovered almost 40 years ago, but it may have existed long before that.

Can I See the Hexagon With a Telescope?

You will need a very powerful telescope to view Saturn’s Hexagon. 

Remember that Saturn is almost 900 million miles away and that in itself makes it harder to view. Adding to that is the fact that the planet’s north pole, where the hexagon resides, is not always tilted towards Earth for us to view. 

Earth’s viewing conditions are tricky as well since such delicate viewing will easily be affected by atmospheric turbulence. 

The best images of this hexagon were obtained by the Cassini spacecraft, which flew to Saturn, so it was closest to the planet and could obtain the clearest photographs. 

Other photographs that we see on the internet are captured by Earth-based observatories located high up in the mountains. 

That being said, it may be possible to view Saturn because the planet shines brightly in our skies. At times when it is above the horizon during darkness, you will find the gas giant on or near the ecliptic

Provided Saturn’s northern hemisphere is tilted towards us (this happens once every 14 to 15 years) and exceptional dark skies, you might discern the hexagon on the north pole with a very powerful telescope

Summary

Saturn’s hexagon is one of the major features of the gas giant, and a significant focus for the Cassini spacecraft to study and photograph when it visited the gas giant. 

It is from Cassini’s images and data that we got to know so much about the feature that we did before. It turns out that the hexagon is formed from an eastward-moving zonal jet that begins much lower in the atmosphere, although scientists aren’t sure about how exactly the jet streams form the hexagonal shape.

Small telescopes won’t reveal the Hexagon, but it is possible to see in the biggest scopes under good conditions.

Until then, we have Cassini’s stellar images to marvel at.


Written by Sharmila Kuthuner