Buzz
Space is truly remarkable. No one can deny that. However, the most awe-inspiring phenomena are located far beyond the boundaries of our solar system—out in the vastness of deep space. In fact, our solar system is rather underwhelming. We’re taught about it as early as first grade: nine planets (or eight, depending on Pluto's status), some unexciting moons orbiting them, the Sun, and that's about it, right? In reality, space holds far more wonders than we could ever fathom, and many of them are much closer to home than you'd think.
10. The Asteroid With Its Own Moon
It might seem logical that anything smaller than a planet wouldn’t have the gravitational force to hold a moon, but that's not always the case. Enter 243 Ida, a small asteroid measuring just 30 kilometers (19 miles) in diameter at its widest. Orbiting it is a tiny moon, just 1.6 kilometers (1 mile) across, called Dactyl. It's the first known binary asteroid system, and the only one we’ve managed to get a close look at with clear images. Since then, we've discovered over a dozen more binary asteroid systems.
9. Io
If there’s a moon that embodies the essence of Hell, it would have to be Jupiter’s moon Io. More resembling a fantastical world than something grounded in reality, Io experiences more volcanic activity than any other celestial body in our solar system. This intense geologic activity is a result of the immense tidal forces between Io and Jupiter, constantly pulling and stretching the moon.
The eruptions on Io can be colossal, spreading volcanic material over 30 square kilometers (11.6 square miles), and are visible from space.
As Io moves through Jupiter’s magnetosphere, it generates immense amounts of electricity, causing lightning storms in Jupiter’s upper atmosphere. But don’t assume Jupiter is the most affected by this interaction—its powerful magnetic belts strip away 1,000 kilograms of material from Io every second. This also supercharges Jupiter’s magnetosphere, effectively doubling its size.
8. Pluto Isn’t Quite What We Imagined
Even though Pluto has been known to exist for quite some time, we actually know very little about this dwarf planet. Take that image above, for example. It’s the clearest photo of Pluto we’ve managed to capture, and even that is a composite of several different shots.
The reason for this is that space is mind-bogglingly vast—ridiculously vast. At its closest, Pluto is a staggering 4.2 billion kilometers (2.6 billion miles) away, a number so enormous that it’s almost impossible for our brains to fully comprehend. The most powerful telescopes we have can only provide a blurry, out-of-focus picture from such a great distance.
But even with these blurry images, we’ve been able to see that Pluto is nothing like we initially thought—a dull, lifeless rock. Instead, its surface is a carbon-rich blend of white, black, and dark orange hues, and we’ve noticed its poles shifting in brightness over time. The most likely explanation is that these are seasonal changes, driven by the faint sunlight that causes methane on the surface to sublimate and escape into the atmosphere (yes, it has one of those, too).
7. Mimas
That’s not a moon... well, actually, it is. This is Mimas, one of Saturn’s moons, and it holds the title of one of the most cratered objects in the solar system. It also bears a striking resemblance to the Death Star. And before you say, “Surely Mimas was the inspiration for the Death Star,” it's worth mentioning that the crater wasn’t discovered until three years after Star Wars Episode IV: A New Hope was released.
Mimas is a bit of a mystery; while its orbit is closer to Saturn than its icy neighbor Enceladus, and both moons are primarily composed of ice, only Enceladus experiences tidal heating from Saturn that melts its ice and forms geysers shooting water into space. This seems odd because Mimas is much closer to Saturn and has a more elliptical orbit, which should lead to more heating than Enceladus, yet it doesn’t seem to happen. We’re still not sure why.
6. Ganymede
Ganymede is the largest moon in the entire solar system, even surpassing the size of Mercury. If it were orbiting the Sun instead of Jupiter, it would be classified as a planet. It’s also unique for having its own magnetic field, something no other moon can boast.
It also possesses a thin oxygen atmosphere, although it’s far too thin to support life. The craters on Ganymede are unusually flat compared to other moons, which hints at underlying geological activity—no surprise considering its vast size and proximity to Jupiter.
5. Saturn’s Enormous Ring
The one thing that immediately comes to mind when Saturn is mentioned is its magnificent ring system. While it’s not the only planet with rings, Saturn’s rings stand out as the most breathtaking example. What we’ve recently discovered, however, is that the ring system stretches much farther than we previously realized.
Made of dust and ice, the ring has remained largely unnoticed for so long due to its near-invisibility. If not observed in infrared, it's incredibly easy to overlook. The sheer scale of the ring is almost impossible to imagine—it starts 6 million kilometers (3.7 million miles) from Saturn and extends all the way out to 12 million kilometers (7.5 million miles). It’s 20 times thicker than the height of the planet itself, and Saturn is no small object. To fill the area the ring occupies, you would need one billion Earths.
4. The Solar System Limits
Despite all we’ve learned about our solar system, there are still basic questions that remain unanswered. For instance, how big is it, really? If you were taught in school that Pluto was the farthest object from the Sun, think again. We later discovered Eris, the largest known dwarf planet, which lies twice as far from the Sun as Pluto. And what’s beyond that? The Oort Cloud, a spherical “cloud” of comets near the Sun’s outer limits.
And what lies beyond? In 1977, we launched two deep-space probes, Voyager 1 and Voyager 2. These probes are still in contact with us 36 years later, and just recently, we realized that Voyager 1 has officially left the solar system. The detection of plasma from stars outside our system confirmed that the probe has crossed the boundary. While this is exciting news, we don’t yet understand all the implications. Now, our goal is to gather as much data as possible before its power runs out, which is expected around 2025.
3. Space
Our solar system is filled with amazing wonders, but we often overlook how vast and empty space really is. It’s called “space” for a reason: it’s mostly just emptiness. (The Earth and the Moon in the image above give a perfect example of just how much empty space surrounds them.)
The Sun makes up an astounding 99.8 percent of the total mass in the solar system. This means that everything else—the massive gas giants, every asteroid, comet, and meteoroid, and smaller planets like Earth—account for just 0.2 percent of the mass, most of which is contained in Jupiter.
The Sun is so immense that its volume is 600 times greater than all the matter in the entire solar system combined. However, it occupies less than one-trillionth of a percent of the solar system’s total volume. The sheer amount of empty space in our solar system is beyond human comprehension.
2. Ceres
Ceres (seen at the lower-left in the image above) is the only dwarf planet located in the main portion of the solar system. Found in the asteroid belt, it dominates the region, making up about a third of the total material there. To visualize its size, imagine launching the entire state of Texas into space—though that image may be a little misleading in terms of its armament.
Due to the blurry boundaries of what defines an “asteroid,” Ceres holds the unique distinction of being both a dwarf planet and an asteroid. In fact, it’s the largest object in the asteroid belt. Beneath its surface, Ceres may contain more water than all the fresh water on Earth combined.
1. Hyperion
Hyperion, resembling a sponge in texture, holds the title of the largest non-spherical moon in the solar system. Its rotation is never quite the same due to the gravitational influence of Titan, a nearby moon that tugs it in various directions.
Hyperion's density is just over half that of water, meaning it would float if placed in a sufficiently large ocean. This low density contributes to its sponge-like appearance, as anything that impacts the moon sinks deeper into it. A floating, spongy moon—if only we could find one that looks like a bar of soap. Oh, wait... we’ve already found one? Well done, NASA.
