Is Pluto still considered a planet in 2018?

Pluto: Planet or Not? Where We Stand in 2018

Remember when Pluto was everyone’s favorite ninth planet? Seems like ages ago, doesn’t it? Well, back in 2006, the International Astronomical Union (IAU) threw us all for a loop and reclassified Pluto as a “dwarf planet.” Cue the collective gasp! So, here we are in 2018, and the question still lingers: Is Pluto really still considered a planet? The official answer is no, but trust me, the story behind that “no” is way more interesting than you might think. It all boils down to how we actually define what a planet is.

What Makes a Planet a Planet? The IAU’s Rules

Before 2006, “planet” was kind of like that vague term everyone used but no one could really pin down. The IAU decided it was time to get specific. They came up with three rules that a celestial body has to meet to earn the title of “planet” in our solar system. Ready for them?

First, it’s gotta orbit the Sun, makes sense, right? Second, it needs to be big enough that its own gravity pulls it into a roundish shape. Think of it like squishing a ball of dough until it’s nice and smooth. But here’s the kicker, the third rule: it has to have “cleared its neighborhood.”

Pluto’s Big Problem: It Hasn’t Cleared Its Neighborhood

So, Pluto orbits the Sun, check. It’s roundish, check. But that third rule? That’s where Pluto stumbles. You see, Pluto lives out in the Kuiper Belt, a crowded area beyond Neptune filled with icy bodies. It’s like living in a neighborhood with a lot of other houses on the same street. Because Pluto shares its space with all these other Kuiper Belt Objects (KBOs), it hasn’t “cleared its neighborhood.”

Honestly, that’s the whole reason for the demotion. The discovery of Eris, a KBO bigger than Pluto, really stirred the pot. If Pluto was a planet, then Eris probably should be too, and who knows how many others would join the club? Suddenly, we’d have dozens of planets!

Dwarf Planet: Not Quite a Planet, But Still Cool

Okay, so what is a dwarf planet then? The IAU has rules for that too. A dwarf planet:

Pluto ticks all those boxes. So, it’s a dwarf planet, along with other cool objects like Ceres, Haumea, Makemake, and Eris.

The Wild West of the Kuiper Belt

Speaking of the Kuiper Belt, imagine a vast, icy donut stretching way, way out beyond Neptune. That’s the Kuiper Belt. It’s packed with millions of icy leftovers from when the solar system was forming. Think of them as the spare parts that never quite made it into a full-fledged planet. These Kuiper Belt Objects (KBOs) are mostly made of frozen stuff like methane, ammonia, and water. It’s a pretty wild place out there!

The Debate Rages On

Even though the IAU made its decision, not everyone is happy about it. Some scientists argue that the “clearing its neighborhood” rule is bogus. After all, they say, no planet has perfectly cleared its orbit. They think we should focus on what an object is made of and how it acts, not just where it is. And after the New Horizons mission gave us those amazing close-up pictures of Pluto in 2015, showing a surprisingly active and complex world, the “Pluto is a planet!” crowd got even louder.

So, What’s the Verdict?

As of 2018, Pluto is still officially a dwarf planet. The IAU made the call based on a specific definition. Sure, the debate will probably keep going for years to come, but Pluto’s reclassification has actually helped us learn a whole lot more about the amazing variety of objects in our solar system. And who knows, maybe someday the definition will change again. Until then, Pluto will always have a special place in our hearts, no matter what you call it.