Saturn—the most familiar of the planets—is looking rather strange these days.
This is because Saturn’s rings are nearly exactly edge-on as seen from the Earth. The problem is, seeing a ‘ring-less Saturn’ was tough until this week, as the world was lost in the Sun’s glare, low in the dawn. Saturn passed solar conjunction on March 12th. The good news is, the view improves in April. Orbiting the Sun once every 29.5 years, Saturn’s rings are tipped open 27 degrees versus its orbit. This means that, from our Earthly vantage point, the rings alternate from wide open, to edge on, to wide again, once every 14-15 years. Saturn’s rings will open towards their widest once again in 2032.
What’s more, the tilt of Saturn’s rings is a complex affair. Not only do they widen, narrow and widen again over a 29.5 year span, but there’s a smaller, five to ten degree wobble annually. This is because our vantage point on Earth is moving around the Sun as well. We had the northern face of the planet tipped Earthward starting in 2009… now, it’s the southern hemisphere of Saturn’s turn, with the northern side giving us the cold shoulder.
A complete ring cycle for Saturn. Credit: Efrain Morales Rivera.
The ring plane was exactly edge on to the Earth on March 23rd, and will be edge on to the Sun on May 6th. When can you start seeing the rings again? Though they span 282,000 kilometers across (that’s almost three-quarters of the distance from the Earth to the Moon), the ring plane is only about 10 meters to a kilometer thick (or an average 100 meters thick in most places). Galileo first spied the rings with his primitive refractor in 1610. His sketches showing a strange twin-lobed world akin to a double-handled coffee cup were a testament to just how bad his optics really were. Christian Huygens was the first astronomer to correctly deduce that the ring plane is entirely detached from the planet itself.
Galileo’s notes, including a small sketch of his view of Saturn. From Galileo’s Letter to Belisario Vinta, 1610/Public Domain.
Today, we know that the rings are snowball-sized particles, likely remnants of a shattered moon. Though every ice and gas giant planet in the solar system is now known to possess a ring system, none are as visually dramatic as Saturn’s. Recent studies suggest that Saturn’s rings are a relatively recent phenomenon, perhaps just 10 to 100 million years old. If dinosaurs had telescopes, a ring-less Saturn may have appeared rather bland to them. What’s more, this view won’t last, as the rings will dissipate from view in the next few hundred million years. We’re lucky to see Saturn in its current glory today.
Following Saturn in 2025
Saturn started the month of April low in the dawn, fresh off of solar conjunction on March 12th. Brilliant -4.6 magnitude Venus makes a great guide to find Saturn, which is over a hundred times fainter at magnitude +1.2. Mercury completes the planetary dawn trio, reaching greatest elongation 27 degrees from the Sun on April 21st.
Be sure to set your alarm to wake up early on the morning of April 25th, when the waning crescent Moon joins the complex sky scene. The Moon misses the planets including Saturn on this pass… the Moon won’t occult Saturn again until early next decade on April 24th 2031.
Looking eastward on the morning of April 25th. Credit: Stellarium.
Following Saturn through 2025, the planet reaches quadrature west of the Sun on June 22nd. This is a good time to see the bulk of the planet cast its shadow back across the rings, in a very 3D-looking appearance.
Saturn goes on to reach opposition on September 21, after which it transitions back into the dusk sky. Saturn’s rings max out 4 degrees wide near quadrature, and close out 2025 with its rings once again tilted a just degree open versus the Earth.
Edge on Saturn and its moons. Credit: Stellarium.
The knife-edge ring plane will knock the overall magnitude of the planet down to +1.2, versus a maximum magnitude -0.54 when the rings are wide open near opposition.
At the telescope, the yellowish 16” disk pales in comparison to Jupiter, though whitish-looking storms have been known to make an appearance on occassion.
Ring plane crossing years are also a good time to spot moon and shadow transits across the disk of Saturn. Common on Jupiter, these phenomena are only seen on Saturn around the years when the rings are edge on. PDS Rings Node and IMCCE France are great sources for moon shadow predictions. You may also want to simply check Stellarium before a night’s observing to see if any events are upcoming. Titan and (very rarely) Iapetus cast good-sized, prominent shadows.
A rare view: Titan’s shadow on Saturn. Credit: Thad Szabo.
“The rings are now close to edge-on, so we will see Saturn’s moons parading across its face for the next 18 months or so,” says astrophotographer Thad Szabo. “Titan orbits Saturn about once every 16 Earth days, so opportunities for shooting a transit come a little less than once every 2 weeks. But you also have to be on the right part of the planet to watch the event, which takes about 5 hours.”
For a time, spectacular views of Saturn were common, thanks to NASA’s Cassini mission. The only spacecraft to orbit Saturn to date, Cassini explored Saturn from 2004 until 2017. Now, we’ll have to wait until the Dragonfly mission heads to Titan starting in July 2028.
It’s strange to think: I started regular skywatching as a freshman in High School in early 1982, and completed one ‘Saturn year’ in 2012 as the planet return back to the constellation Virgo… if fate smiles on me, I’ll complete my second Saturnian year in 2042. Let’s see, by then I’ll be…
Be sure to check out familiar Saturn this season at dawn, as it continues to present a strange edge-on view.