Is Pluto a planet? Well, what do you think? 

Many people have formed strong opinions on this topic in an ongoing cultural conversation — you might even have one yourself.

Pluto had been known as the ninth planet of our solar system ever since it was discovered in 1930. And now, it’s the 20th anniversary of when that changed: Pluto’s demotion.

Weather in your inbox

Forecast Location

Sign Up

By signing up you agree to the Terms & Privacy Policy. Unsubscribe at any time.

Fascinatingly, this became a huge debate. There was, on one side, the reasoning of scientific taxonomy and, on the other, a loud cultural public opinion that was also rooted in historical precedent.

We talked about it in our office, and there’s one truth for certain: even if Pluto’s scientific classification changed, it lives on as a planet in the hearts of many. And remnants of it can be found in our world, through physical media like old textbooks and educational videos and games from the early 2000s.

“I literally grew up with Pluto as a planet,” Stephanie Quick, our lead performance marketing manager, shared. “To this day, I won't tolerate anyone saying Pluto isn't a planet — hold firm, little rock!”

Get More of Our News on Google

Set The Weather Company as a 'Preferred Source' to get quicker access to the news you value.

So, as an ode to Pluto, here’s both some science and story about its journey through time. 

Pluto’s discovery: the search for Planet X

The 1930s were a period of feverous planet hunting. And finding a mysterious, potential ninth planet — known as Planet X — was of particular interest.

In 1906, Percival Lowell started a project to find it at the Lowell Observatory. He searched until his death in 1916 with no success. 

At least, that’s what he thought, but unknown to him, on March 19, 1915, his observatory had in fact captured two faint images of Planet X. 

(MORE: Close-up images of Pluto have scientists “reeling”)

The search paused and then finally continued more than a decade later with Clyde Tombaugh. He spent a year systematically comparing photographs of the night sky in pairs taken two weeks apart, trying to determine whether any objects had shifted position.

On February 18, 1930, he found it: Planet X.

Pluto’s name: chosen by an 11-year-old girl

The discovery was spread across the globe. And the Lowell Observatory received 1,000 suggestions from all over the world.

The winner was an eleven-year-old schoolgirl from Oxford, England, Venetia Burney. She received five pounds as a reward.

Her name? Pluto.

(MORE: Scientists solve the mystery of why Pluto's weather is unpredictably cold)

Burney was interested in both classical mythology and astronomy. For what was presumably a very dark and cold world, she thought the name for the Greek god of the underworld was a perfect fit — and so did the observatory. 

Pluto’s founding: a family in the Kuiper Belt

The truth is, astronomers have argued since the late 1990s whether Pluto is a planet. 

It began with scientists theorizing about the possibility of a bunch of small, icy bodies beyond the orbit of Neptune, of which Pluto could have been the first discovered.

(MORE: Pluto and its moons are much different than anticipated, scientists say)

These would become known as Kuiper Belt Objects, and several were discovered. One in particular, Eris, appeared to be larger than Pluto. And now many newly found celestial bodies could be classified as planets.

This sparked a whole new conversation on what the formal definition of a planet should be.

Pluto’s demotion: a dwarf planet

It finally came down to a vote at a meeting of the International Astronomical Union. 424 astronomers cast a vote; notably, by opponents of the final decision, this was less than 5% of the world's astronomers.

On August 24, 2006, Pluto was officially reclassified as a dwarf planet. 

(MORE: A team of researchers is lobbying for Pluto, and about 100 other celestial bodies, to be classified as planets.) 

The astronomers had decided that it made more sense to consider Pluto a dwarf planet among many objects in the Kuiper Belt rather than a planet like the other eight in our system. If we wanted to call Pluto a planet, we would have to call a bunch of other things planets, too.

The new definition included three things:

1. It must orbit the sun.
2. It must be large enough to become a round shape through its gravitational orbit.
3. It must exert orbital dominance and “clear the neighborhood” surrounding it.

Pluto fit the first two rules. But it wasn’t big enough to satisfy the third; it simply had too much “space junk” and rocks orbiting around it. Its gravity wasn’t strong enough.

Pluto’s admiration: public outcry and love

This became known as “Pluto’s demotion.” Pluto, of course, didn’t experience a pay cut or a change in its daily work tasks. But regardless, this choice of words upset the masses.

Pluto’s characteristics frame it a bit as an underdog. It’s small and cold and faraway.

Pluto is only about half the width of the U.S. at 1,400 miles wide. It’s 3.6 billion miles away from the Sun and holds an average temperature of -387 degrees Fahrenheit. 

These scientific features had some impact on its emotional appeal — and a “demotion” must have meant it was under attack.

(MORE: Pluto has tropic and arctic regions, New Horizons scientists say)

NASA's New Horizons mission performed a Pluto flyby. It was the first spacecraft to explore Pluto up close, flying by the dwarf planet and its five moons in 2015.

Just as Pluto was named by a girl, women uniquely make up about 25% of the Pluto flyby team — in the astronomy world, that’s a lot.

The mission’s very own operations manager, Alice Bowman, has taken a stand for the little planet.

“I can't imagine anyone saying that Pluto is not worthy of planet status,” she said in an interview with PBS. “I mean, it's just great!

In the first round of Pluto images from this mission, one of the details that deputy project scientist Cathy Olkin noticed was a heart shape on Pluto’s surface.

And it was a stab at nostalgia for many; learning the nine planets is a core childhood memory. 

“I wondered about the ‘my very educated mother just served us nine pizzas’ phrase,” an assignment editor in our office, Brandon Burton, mused. 

The phrase had been ingrained in the minds of a generation to remember the order of the nine planets from the sun by using the first letter as a reminder (Mars, Venus, Earth, etc.).

“But it seems that the mother now just serves nachos or noodles according to Google,” he said.

So, after reading this, has your mind changed? Is Pluto a planet to you? Were you swayed by the scientific logic? Or swooned by heartfelt symbolism? 

I love science. But I think my heart is one of the many captured by Pluto, and the vision of it as a planet, as I was first taught, remains unchanged.

Content writer Ada Wood enjoys exploring the stories that science and climate teach us about our natural world and how it influences the way we live in it.