Why Saturn’s rings have disappeared, and when they’ll be back

Amateur astronomers have lost one of the jewels of the night sky – the rings of Saturn.

The majestic planet has slipped from Earth’s view, effectively hidden behind the sun, and University of Southern Queensland astronomer Professor Jonti Horner said by the time Saturn re-emerged, the rings would be virtually invisible.

“The long and short of it is Saturn’s rings are very broad but very thin,” he said.

Hubble Space Telescope images of Saturn in various phases.Credit: NASA

“...Saturn has seasons, and in the summer for Saturn’s northern hemisphere, the northern hemisphere is tilted towards the sun and the southern hemisphere is tilted away. That means you can see the rings tilted towards us, looking nice and big and fat.

“A quarter of an orbit later, it’s passing through what will be the equinox for Saturn and that’s the point at which the equator’s pointed towards the sun – so neither the north pole or the south pole is tilted away – and that means that the rings are also pointed towards the sun.

“So from our point of view, we’re pretty much seeing them edge on.”

Given the rings’ thickness could be measured in the tens of metres in most places, that made them all but invisible from Earth’s vantage point more than 1.5 billion kilometres away.

It all made for a bad 2025 for Saturn lovers.

Horner said the rings would reappear “only slightly” as Earth bobbled through Saturn’s orbital plane, but would disappear again in November.

The rings would be hard to spot in the sun’s glare early next year, but by about May 2026 they should be back in all their glory, Horner said, and remain that way for about 14 years.

“Some of the more clickbaity kind of commercial stations were saying ‘Saturn’s rings are disappearing – this is your last chance to see them’,” he said.

University of Southern Queensland astrophysicist Professor Jonti Horner.

“Well, no – this happens all the time.”

There were theories, however, that Saturn’s rings were transient and could disappear within 50-to-200 million years, while other theories suggested they were as old as the gas giant they orbited.

“We just don’t know,” Horner said.

“The challenge here is it’s less than 400 years since the rings were really discovered – Galileo in 1610 observed Saturn with a couple of blobs next to it, so that could be the discovery of the rings – but it’s really after that, when they were resolved.

“So we’ve been watching them for 400 years, and only with really advanced scientific instruments and techniques for 40 years, and we’re trying to predict what will happen on timescales of millions of years.”

The Toowoomba-based USQ has Queensland’s only professional astronomical observatory at Mount Kent, about 25 kilometres out of town in a designated dark-sky site.

“The skies are good enough that we can build that near Toowoomba, rather than having to go in the middle of nowhere,” Horner said.

From Mount Kent, Horner and other researchers search for and study exoplanets orbiting distant stars, discovering more than 100 to date.