Why Saturn’s rings appeared to have vanished

There are few sights in our Solar System as stunning as Saturn’s bright, sweeping rings. But this Sunday, November 23, the gas giant looked strangely bare.

For a short while, its famous rings seemed to “disappear” from view, not completely, but enough to surprise anyone looking through a small telescope.

This rare moment, which happens roughly once every 13 to 15 years, is the result of an optical illusion, English astrophotographer Damian Peach told The New York Times. 

Here’s why Saturn appeared ringless

The logic behind this phenomenon is Saturn’s alignment. The planet is tilted at about 26.7 degrees and takes around 29.4 Earth years to go once around the Sun. Because of this tilt, half of its long orbit has the planet leaning towards the Sun, and the other half leaning away.

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Its rings are tilted at the same angle, so as Saturn moves, the rings seem to shift position when we look at them from Earth.

Once every 13 to 15 years, the rings line up perfectly edge-on with our planet.  When this alignment occurs, we see only the very thin edge of the rings, and they are incredibly thin, only a few tens of metres thick in many areas.

So when the rings turn edge-on, they reflect almost no sunlight and appear to “vanish”. And as Saturn continues its orbit, the tilt changes again, and the rings slowly come back into view.

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Philip Nicholson, an astrophysicist at Cornell University, and his team used the James Webb Space Telescope to take advantage of the reduced glare and study Saturn’s faint e-ring during the near crossing.

Formed by icy plumes from the moon Enceladus, this outer ring may hold clues about carbon atoms, and thus perhaps the habitability of the moon’s underground ocean.

Has this happened before?

Yes, this isn’t the first time Saturn’s rings have seemed to fade from view.

The most recent alignment happened in March, and the next complete “disappearance” is expected in 2038. After this weekend, the rings are now slowly starting to open up again and will look their widest from Earth around late 2027.

A single crossing in 2009 was impossible to see as it was blotted out then by the glare of the sun, and could not be observed. The last three observed from Earth were in 1995 and 1996.

But there’s a bigger, long-term story too.

Back in 2018, Nasa confirmed that Saturn will eventually lose its rings for good. The planet’s gravity and magnetic field are constantly pulling small particles from the rings towards the planet, a process scientists call “ring rain”.

James O’Donoghue, a Nasa scientist, explained that Saturn is losing enough material to fill an Olympic-sized swimming pool every half hour. If this continues, the rings could disappear completely in about 300 million years, maybe even sooner.

So while the “vanishing rings” we see now are just a brief optical illusion, the rings themselves won’t be around forever.

What are Saturn’s rings made of?

Saturn’s famous rings are not a single solid band. They’re actually made up of billions of tiny pieces of ice and rock. Nasa’s Cassini spacecraft found that these fragments can be as small as grains of dust or as large as mountains.

Scientists believe the rings are relatively young in cosmic terms, likely formed around 100 million years ago. The most widely accepted theory is that two icy moons collided, and the debris from that violent impact spread out around Saturn. Over time, this debris settled into the bright rings we see today.

Other giant planets such as Jupiter, Uranus, and Neptune also have rings, but theirs are extremely thin and faint, sometimes barely visible even through a telescope. Saturn, however, is different. Its ring system is massive, stretching across a distance almost five times the diameter of Earth.

Astronomers divide this giant ring system into seven main sections, each made up of countless smaller ringlets and patterns. Together, they form the stunning sight that makes Saturn one of the most recognisable planets in our sky.

With input from agencies