Honestly, we need to talk about Pluto. It’s been twenty years since that chaotic meeting in Prague where a room full of astronomers decided Pluto wasn't a "real" planet anymore. People were mad. Some are still mad. But if you haven't looked at a photo of that frozen little rock since the mid-2000s, you're missing out on the most interesting glow-up in the solar system.
Basically, we used to think Pluto was just a dead, boring ball of ice. Then NASA’s New Horizons spacecraft screamed past it at 36,000 miles per hour in 2015, and everything changed. It turns out Pluto is less like a cold rock and more like a living, breathing world with a beating heart and—wait for it—maybe even a secret ocean.
Here is the reality of what’s actually happening out there on the edge of the Kuiper Belt.
1. It Has a Giant "Beating" Heart
If you look at any high-res photo of Pluto, you can’t miss it. There’s a massive, bright, heart-shaped glacier officially named Tombaugh Regio.
It’s huge. We're talking 1,000 miles across.
But it’s not just a pretty shape. The left side of the heart, a region called Sputnik Planitia, is actually a massive basin filled with nitrogen ice. Because nitrogen is softer and more "flowy" than water ice, this glacier is constantly churning. Heat from deep inside Pluto makes the nitrogen rise, cool, and sink back down in a process called convection.
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It’s literally a world that refreshes its own skin. This is why you don't see many craters there—the "heart" is constantly erasing the evidence of asteroid impacts. It's essentially a geological fountain of youth.
2. There is (Probably) a Liquid Ocean Hiding Inside
This is the one that really trips people up. Pluto is almost 4 billion miles from the Sun. It is cold. Like, -380°F cold. You’d assume it’s frozen solid all the way through, right?
Well, maybe not.
Scientists like Carver Bierson and Adeene Denton have been looking at the cracks and "stretch marks" on Pluto’s surface. If Pluto had started as a cold ball of ice that slowly warmed up, the surface should look crumpled. Instead, it looks like it's been stretched out from the inside.
The leading theory now? Pluto had a "warm start." It likely formed with a liquid ocean that is still partially liquid today, buried under a shell of ice 20 to 50 miles thick. To keep it from freezing solid, that water is probably super salty—kinda like the Great Salt Lake but floating through deep space. If you could somehow drill through the ice and jump in, you’d probably float like a cork.
3. Pluto’s Atmosphere is "Falling" to the Ground
Most planets have a permanent atmosphere. Earth's air stays put. Even Mars, with its thin air, keeps its gas. Pluto is different. Its atmosphere is a seasonal temporary worker.
Pluto’s orbit is a mess. It’s not a neat circle; it’s a stretched-out oval. When Pluto gets "close" to the sun (which is still incredibly far), some of the nitrogen ice on its surface turns into gas, creating a thin, hazy atmosphere.
But as it moves away into the dark, it gets colder.
Research from 2024 and 2025 suggests that the atmosphere is currently in the middle of a "collapse." As Pluto gets further from the Sun, the gas is literally freezing and falling to the ground as nitrogen snow. By 2030, the atmosphere might be completely gone, leaving Pluto as a naked, airless rock until it swings back around toward the Sun in another couple hundred years.
4. It’s Part of a "Double Planet" Duo
You've probably heard of Charon, Pluto’s biggest moon. But calling it a "moon" is sorta selling it short.
Charon is half the size of Pluto. For comparison, our Moon is only about 1/4th the size of Earth. Because Charon is so big, it doesn't actually orbit Pluto in the way you’d think. Instead, Pluto and Charon both orbit a point in empty space between them.
Imagine two people holding hands and spinning in a circle. They’re both moving around a center point. That’s Pluto and Charon.
They are also tidally locked. This means the same side of Pluto always faces the same side of Charon. If you lived on one side of Pluto, Charon would just hang in the sky, never rising or setting. If you lived on the "back" side of Pluto, you’d never even know it had a moon. It’s a weird, permanent cosmic stare-down.
5. The "Demotion" Was Actually About Math, Not Hate
People take Pluto's "dwarf planet" status personally. But the International Astronomical Union (IAU) didn't do it to be mean. They did it because we started finding too much stuff.
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In the early 2000s, astronomers found Eris, which is actually more massive than Pluto. Then they found Haumea and Makemake. If Pluto stayed a planet, we’d have to call all those other things planets, too. We’d eventually have dozens, maybe hundreds of planets in our solar system.
The "rule" Pluto failed is that it hasn't "cleared its neighborhood." Basically, Pluto is a bit of a slob. It shares its orbital path with a bunch of other junk in the Kuiper Belt.
Alan Stern, the guy in charge of the New Horizons mission, famously hates this definition. He argues that if you put Earth in Pluto's spot, Earth wouldn't be able to "clear its neighborhood" either because the space is just too big. So, depending on which scientist you ask, Pluto is either a "dwarf planet" or a "small planet that’s just in a crowded neighborhood."
What You Should Do Next
If you want to actually see Pluto for yourself, don't expect much from a backyard telescope—it'll just look like a tiny, faint star. Instead, check out the NASA New Horizons image gallery. They have the raw data from the 2015 flyby that shows the "snakeskin" mountains and the red "tholin" stains that make Pluto look like it’s covered in rusted tar.
You can also track the Pluto Occultation projects. Since the atmosphere is currently freezing and disappearing, astronomers are racing to watch Pluto pass in front of distant stars to measure how fast the air is vanishing. It’s one of the few times we get to watch a planet-wide climate shift happen in real-time.
Finally, keep an eye on the proposed Pluto Odyssey mission. While it's still in the "maybe" phase for the 2030s, it would be an orbiter designed to actually stay at Pluto rather than just flying past. That's the only way we'll ever know for sure if that underground ocean is actually there—and if anything is living in it.