Ask any astronomer if they can remember a moment that inspired them to become an astronomer and there’s a good chance they’ll reply that they saw Saturn through a telescope when they were a child. There are many good reasons why this beautiful planet features so often in the childhood memories of those who love astronomy.
There really is nothing else out there that hits the eye like Saturn. Not yet anyway. Maybe one day we’ll have some radically different technology that can give us detailed views of exoplanets that look similar, but for now, it stands alone as the quintessential ringed planet that every kid thinks of when first drawing pictures of space. And it really does look almost cartoon-like when you see it through a telescope for the first time. Yes, other planets have rings. Notably Jupiter and Uranus (sorry to disappoint the comedians, it’s pronounced Yoo-ra-niss), but they’re nowhere near as bright and dramatic as Saturn’s.
Being composed mostly of water-ice, the rings reflect a lot of the sunlight that strikes them, making them appear pretty bright for 1.5 billion kilometres away and averaging 10 metres thick. Yes, 10 metres. One tenth of a rugby field excluding the in-goal areas. That’s crazy right? We expect big numbers in astronomy so imagining Saturn’s rings being as thick as a two-story house, is quite surprising. To be fair, they are a lot thicker in certain areas but that’s the average, spread over the roughly 300,000km they span from edge to edge.
And that’s almost as far as the distance to the moon from Earth.
Exactly how the rings formed is still quite open to enquiry, scientifically speaking. We can’t wind back the clock and watch it unfold but the evidence points to one or more icy bodies – such as a past moon of Saturn – being torn apart through tidal forces, stripped of an icy crust, a collision with another object or some combination of these.
Over time, collisions between the individual particles would average out the motion and form the flat disk. This is the same basic reason the eight planets orbit the sun on the same plane. More recent evidence from the Cassini mission suggests that the rings may be younger than initially thought. Even as young as only 10 million years old. Basically a blip in the lifetime of Saturn the planet. Whether they are young or old, how they formed or how long they will last, Saturn’s rings make it a sight like no other.
September and the remainder of 2023 are going to be great for viewing Saturn.
In September it has already risen before sunset and is up most of the night. By late December it will be setting a couple of hours after sunset.
