Saturn is the jewel of the solar system, with its gorgeous rings and continuation of strange moons. It’s the faintest of the naked eye planets – technically Uranus is Sometimes bright enough to see, although you need good eyesight and a very dark site, but still fairly easy to spot among the stars.
If you’re an early riser (or a late partier), then now is a good time to seek out Saturn, not because it’s brighter or closer to Earth than usual, but because it recently made the news. New research indicates that its rings are relatively young, from a cosmic perspective, and astronomers have also just announced the discovery of a whole host of tiny Saturnian satellites that make the planet the current record holder for the largest number of moons.
Saturn currently reaches the crest of the horizon in early morning local time, and about an hour later rises high enough to be spotted low in the southeastern sky. If you get up shortly before dawn, it will be about 25 degrees above the horizon, or about 2.5 times the width of your outstretched fist, a universal unit of measurement among astronomers. Don’t confuse it with nearby star Fomalhaut, which is closer to the horizon than Saturn and has almost exactly the same luminosity. Jupiter is closer to the eastern horizon (bottom and left of Saturn, for northern hemisphere observers), but it is 15 times brighter and much easier to spot.
If you’d rather avoid a pre-dawn sight, then the wait is also acceptable: Saturn’s rings and moons aren’t going to disappear (on a human scale anyway). And as summer progresses, the planet rises earlier and rises higher in the sky at a more reasonable time. In late June it rises around midnight in many places, for example, and in late August it reaches the sky looking at the sweet spot: it rises at sunset and stays awake all night.
Through binoculars, Saturn can appear elongated or oval because of its rings. The sharper view from a small telescope will reveal the rings more clearly. While using one, you might even spot a few of the planet’s moons; its largest, Titan, is larger than Mercury and usually appears as a faint “star” adjacent to Saturn.
If you brave the first few hours to observe the gas giant, take a moment to contemplate what you really see. The pale and resplendent orb, so small in our sky, is a giant nine times wider than Earth and 95 times more massive. And despite centuries of observations, we are still learning about this ringed wonder.
Saturn is iconic among its planetary siblings because of its rings, of course. Jupiter, Uranus And Neptune all also have rings, but these are thin, faint, and difficult to see without spacecraft or powerful telescopes. Saturn’s rings stretch an incredible 175,000 miles (282,000 kilometers), or three quarters of the distance between Earth and our Moon!
Although they appear solid, Saturn’s rings are actually made up of countless chunks of near-pure water ice, likely the remnants of a shattered moon. The largest pieces are probably less than ten meters in diameter…most resembling the size of the ice cubes you put in your drinks. Although the rings haven’t appeared to change much since humans began observing them through telescopes in the 1600s, their age and longevity have been contentious issues among experts for much of that time.
More recently, the evidence is piling up that the rings are much younger than the planet’s about 4.5 billion years old. THE Mission Cassini provided much of the data for this; the spacecraft orbited the planet for 13 years and sent a wealth of information to Earth.
new research, just published in the journal of planetary sciences Icarus, reinforces the idea that not only are the rings young, but also that they won’t last forever.
Micrometeoroids – tiny space rocks that crisscross the solar system – played a key role in this new timeline. When they hit particles in Saturn’s rings, there are two general consequences. The first is that micrometeoroid dust pollutes and darkens the rings’ pristine water ice. The other is that these small collisions sap the orbital energy of particles in the ring, which respond by moving toward Saturn. Together, these effects should cause particles in the ring to become dirty over time and eventually rain down on Saturn itself.
With the Cassini data in hand, the scientists quantified these effects, finding that the rings are probably no more than 120 million years old, which is quite young for a planetary system. To put this into perspective, if the first Cretaceous dinosaurs had invented telescopesthey would have seen Saturn without rings!
The researchers also found that the rings are eroding at a rate that means they will disappear within 15 to 400 million years. That’s a long time in human terms, but it’s only a fraction of the age of the solar system.
Ironically, although Saturn’s rings are fading, it seems to have an increasing number of moons. It’s not literally or physically – we just get better at finding them.
Scientists just announced a new pass of 62 moons around Saturn, bringing the planet’s total to more than 140, surpassing Jupiter’s previous record of about 90.
Researchers actually spotted several of these moons during observations in 2019 using a clever technique to improve their visibility, but these tiny satellites were very faint and didn’t move much between observations. To confirm them, astronomers needed to get more data. Over the past two years, they’ve done just that and identified the reality of moons, most of which are only a few miles across.
How many moons could Saturn actually have? Well, that depends on what you mean by “moon”. There are hundreds, certainly, maybe thousands over a mile or so. But if you count each ring particle as a moon, then the answer is trillion. The problem here is that we don’t have a good definition of what makes a moon, especially when it comes to the lower size limit. So in that sense, trying to decide which planet has the most is kind of silly.
But still, if you venture out early and gaze at Saturn in the pre-dawn spring sky, remember that you are now armed with knowledge that would make astronomers of just a few decades ago jealous. Hundreds of mountain-sized moons surround Saturn. Its rings are young and ephemeral. In a very real sense, we’re lucky to be there to see them at all.