Planet Appreciation: Saturn

I have to admit, Saturn is one gorgeous planet, and my astrophotography does not do it justice.

But what makes Saturn so beautiful?

Saturn and its rings in 2018
NASA, ESA, A. Simon (GSFC) and the OPAL Team, and J. DePasquale (STScI)

Is it the Rings?

Saturn actually has many rings, ringlets, divisions and arcs. Galileo was the first person to view them, but he didn’t know what they were. Christiaan Huygens was the first person to propose that Saturn had rings.

We’ve sent many spacecraft to Saturn to observe its rings. Pioneer 11 and Voyager 1 took multiple photos of Saturn, and led to the discovery of 2 new rings. Voyager 2 and the Cassini spacecraft took very detailed images that showed all the ringlets and divisions inside the rings.

1920px-Saturn's_rings_in_visible_light_and_radio

Saturn has 7 main rings. The B and A rings are packed with ice, but the C ring is split into lots of gaps and ringlets. The biggest ring is the E ring, and is 300’000 km wide, but the biggest gap is the Encke gap. Inside the gap is a Moon called Pan, which makes ripples in the ring!

The order of the rings is self-explanatory and so easy to remember; they go from the D ring to the A ring, and then from the F ring to the Phoebe Ring (crazy how the alphabet does that!) What do you mean it’s confusing?

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The rings are mostly made up of ices like water ice, from tiny specks to a few metres wide. Some rings, like the Janus/Epimetheus Ring and Pallene Ring are made up mostly of dust particles. When moons leave dust behind, they create ring arcs, for example the Anthe ring arc which was made from dust blown off of the Moon Anthe from impacts.

Moons inside the Rings

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Ripples caused by Daphnis. Image Credit: NASA / JPL / SSI

Within some gaps are actual Moons and moonlets! A small Moon of Saturn, Daphnis, is nicely snuggled in the Keeler Gap within the A ring. Daphnis’ gravity moves the ice in the ring, making ripples as it orbits.

 

 

 

Another moon, Pan, orbits Saturn inside the Encke Gap. This picture from Cassini shows Pan’s orbit inside the Encke gap.

PIA06534_Encke_Division

Saturn also has many moonlets, which are very small moons. A moonlet has been found in the B ring, and four have been seen in the A ring, for example Santos-Dumont in the picture below.

A_Ring_propeller__Santos-Dumont__(PIA_21433)
Disturbances caused by Moonlet Santos-Dumont. Image Credit: NASA / Jet Propulsion Lab-Caltech / Space Science Institute

Or The Hexagonal Jet Stream?

PIA21351
NASA/JPL/SSI

This ginormous storm is by far the coolest storm around, sorry Jupiter!

Actually Jupiter also has an awesome polar storm too, but that will be in another post.

After being observed by Voyager I and the Cassini Orbiter spacecraft, astronomers discovered a remarkable (and very old) hexagonal jet stream at the North Pole of Saturn.

In the middle of the jet stream is a polar vortex, a very common feature on planets. Earth gets a lot of them, but our oceans are able to transfer heat out of the vortex and let it dissolve without too much damage.

Each side of the hexagon is slightly larger than Earth’s diameter, with the whole stream being about 2.4 x Earth’s diameter, and has a speed of about 320 km/h. The average wind speed in the UK in 2019 was 15 km/h, just for context.

image description
Recreation of Saturn’s jet stream, by Ana Aguiar et al.

Our current research shows that this storm may have been caused by a planetary wave travelling around Saturn and interfering six times with itself to produce this standing jet stream, and this wave was caused by disturbances from a large difference in wind speeds where the jet stream is. Astrophysicist Ana Aguiar and her team were able to recreate the conditions of Saturn’s North pole on a laboratory scale, and achieved a 6 sided standing jet stream.

 

All I can say is that this Cronian storm is unlike any other in the solar system.

IDL TIFF file
An amazing colour image of the storm by Cassini Orbiter. Image Credit: NASA/JPL-Caltech/SSI.

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And as a little treat…

Here’s my first ever piece of astrophotography. As you can clearly tell, it’s Saturn.

SaturnBarz

6 comments

  1. Saturn was the first planet I ever saw through a telescope. Personally, I’ve come to appreciate Jupiter a bit more, because of the banding and the moons. But seeing those rings for myself… that was the first time space wasn’t just something I read about in a book or saw on T.V. That was the first time space was real to me.

    Liked by 1 person

    • Saturn was also my first planet, I could just make out the gaps in the rings, and I luckily had a gigantic telescope to view it with. Usually seeing something on the screen or through a lens just isn’t real enough for me, but not when it comes to looking through a telescope! It’s just completely different to a camera lens.

      Liked by 1 person

    • You’re right! We need some more Mercury appreciation. Not even spacecraft organisations like Mercury that much, and it’s awful!

      Like

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