Jupiter has four sets of them made up of dust and particles due to its moons being bombarded by meteors. Uranus has 13, and recent thermal imaging shows they are the same temperature as the boiling point of liquid nitrogen. Saturn’s are made up of fragments of asteroids and comets, with pieces ranging in size from small icy specks to looming mountains.
We’re talking about rings, and we all know Earth isn’t on the list of the Solar System’s ringed planets. But let’s say that it was: What would that mean for life on Earth? If Earth did have rings like Saturn our sunsets would be an incredible spectacle, but would anyone be around to enjoy the view? The idea isn't that farfetched as the Earth may have had rings a very long time ago, the result of a cataclysmic planetary crash.
For a short time, the Earth once had rings
At one point very early on in its history, Earth may have had a ring of rock debris around it. The giant impact theory, sometimes referred to as the Big Splash, was first proposed by geochemist Alex N. Halliday in 2000. It suggests that the Moon formed from the ejecta of a collision between the proto-Earth and a Mars-sized planetesimal half the diameter of Earth named Theia, 4.5 billion years ago.
This giant impact, thought to have been 100 million times more powerful than when the Chicxulub asteroid hit our planet and wiped out the dinosaurs, may have sent a ring of matter hurtling into Earth’s orbit. This rocky debris eventually formed a new celestial body that our planet is now tidally locked into – the Moon.
How could Earth get rings today?
It’s true that having planetary rings visible above us might be a little more impressive than just a dusty grey rock that looks like a faint lightbulb that doesn’t have an off switch. If we did wake up to rings tomorrow, we might soon be wishing the Moon and the Sun were the only things capturing our attention. And here's why:
In 1848 French mathematician Edouard Roche calculated that if a large body were to approach a planet too closely, it would be torn apart by the planet's gravitational forces. The point where an asteroid or comet began getting a little too close for comfort and be obliterated into smaller chunks of rock is now called the Roche limit.
The exact distance of where this limit is depends on the size, mass and density of the two objects involved. For the Sun, anything coming within 1.3 million kilometers of it (a little less than a million miles) is going to get a rude awakening by being ripped apart. The Earth would do the same to an average-sized comet from approximately 18,000 km (11,185 miles) away. The Moon’s Roche limit would be 9,500 km (5,900 miles).
The rings around Earth that would form from the debris field of the torn Moon would be approximately 5,000 kilometers (3,100 miles) wide and around 9.5 meters (31 feet) thick. But unlike Saturn’s icy rings, including one that is 7,000 times the diameter of the planet, ours would be made of nothing but rock. Saturn has a little more distance between it and the Sun — 1.4 billion kilometers (850 million miles) — compared to Earth’s 150 million kilometers (93 million miles), so the odds would be slim you’d ever find ice in Earth’s rings.
Peering skywards, you’d have a permanent view of Earth’s rings but they would stretch across the sky differently depending on your location on the globe. This would be affected by your position in the northern or southern hemisphere and which direction you happened to be looking.
In the northern hemisphere, say in New York City (~40° north), you would see the rings when looking south. They’d be impossible to miss, covering up to a third of the sky.
In a place like Quito, Ecuador, on the equator (0.18° south), the sight would be very different though. Since you'd be looking in the same plane as the rings and standing perpendicular underneath, all you would see is a bright line reaching from horizon to horizon.
The more north or south you go from the equator, the larger the rings would appear. In Rio de Janeiro (23° south), they would become wider and more visible. In places as far north as Iceland, they’d appear just above the horizon.
While the rings would make for a breathtaking sight in the sky, they would also come with one major drawback: Their shadows. Depending on the time of day, the rings would cast large shadows that creep over the Earth's surface, causing high winds between dark and sunny areas as the temperature drops in the shadowy regions. Make sure you’ve got a heavy coat and a very warm blanket for when the shadows kick in — these areas would be almost inhospitable due to the extreme cold.
How would the sudden appearance of rings change life on Earth?
Communications satellites are often situated around Earth’s equator, and we’d be dealing with the after-effects of them being stuck in perpetual rock storms knocking them offline. If you want to snap a selfie of you with the rings looming over your shoulder like a rainbow for your social media accounts you’re going to be a little disappointed your subject matter is the reason why internet access would be severely limited.
Exploring the cosmos might be off the table completely. Do you know anyone who would want to pilot any kind of spacecraft through a wall of hurtling rocks?
More importantly, insta-rings around the planet would of course disrupt ecosystems across the globe. If not enough direct sunlight was making it through the rocky rings, photosynthesis and its life-giving process of capturing light energy to convert water into the oxygen we need to breathe would be dangerously impacted. Without enough oxygen, things start to look bad for the inhabitants of Earth.
What if Earth always had rings?
If Earth had rings from day one and kept them around, we’d be dealing with a much different story. As long as oxygen and sunlight were still in the mix, chances are evolution would take of the rest and we’d still be around. But we’d have to develop other means of communication since we wouldn’t be able to send satellites into an orbit full of rocks.
The rings of Saturn are only expected to be around for another 300 million years at most, and some experts think it could be less than 100 million. And like Saturn, Earth’s rings probably wouldn’t last for eternity. Eventually, they’d call it a day and start falling apart, piece by piece.
When that starts to happen, the future Earthlings who have managed to survive the planetary extremes the rings above their heads placed them in had better have some decent helmets around, because being armed with an umbrella when it starts raining rocks isn’t going to do the trick.