It Took Pluto Nearly 250 Years to Finally Orbit the Sun — Here's Why

• Since Pluto is located so far from the sun, it takes around 248 Earth years for Pluto to orbit the sun.

• Pluto’s orbit around the sun is not only a very long journey, it’s also elliptical, resembling a smooshed circle as it moves through space.

• Pluto is 39 times farther away from the sun compared to Earth, which means it’s frigid and unlikely to be home to life.

Pluto is the farthest planet, or rather, dwarf planet, away from the sun. It was renamed a dwarf planet in 2006 by the International Astronomical Union because of its size and that other planets may cross its orbit.

But whether or not it’s considered a planet doesn’t change our fascination with this celestial body. It’s 39 times farther away from the sun compared to Earth, which means it’s frigid and unlikely to be home to life. And thanks to its place in the Solar System, until recently, we knew little about it.

Luckily, also in 2006, the New Horizons spacecraft launched and sprang into orbit, forever changing what we know about Pluto. From it, we’ve gotten to see Pluto up close and personal, including its surface marked by mountains — blocks of ice blanketed in methane — along with valleys, plains, and craters.

We know it’s extensive, but how long does it really take Pluto to orbit the sun? According to David Weigel, planetarium director at the U.S. Space & Rocket Center in Huntsville, Alabama: a long time. Since Pluto is located so far from the sun, it takes around 248 Earth years for Pluto to orbit the sun. And it doesn’t do it in a circular fashion.

“Pluto is situated between 30 and 49 astronomical units away from the sun,” says Weigel. To put that in perspective, each astronomical unit is the distance from the Earth to the sun, which is around 93,000,000 miles. It’s so far away that it takes a long time to travel the distance, which is also impacted by the sun’s gravity, the collective gravity of the Solar System, and its small size.

Read More: Chaos in Our Solar System Could’ve Caused Planet X’s Theoretically Wide Orbit

Pluto’s orbit around the sun is not only a very long journey, it’s also elliptical, resembling a smooshed circle as it moves through space. Earth’s orbit around the sun, which takes 365 and 1/4 days, is much shorter and also more circular.

“It can get so cold when it’s farthest away from the sun that its atmosphere effectively freezes out,” says Weigel. This means that the atmospheric gases condense into a solid state due to a dip in temperature. The New Horizons spacecraft showed this when it flew by around a decade ago.

Interestingly enough, Neptune, which is the closest planet to Pluto, crosses orbits with the dwarf planet. Pluto is inside Neptune’s orbit for a whopping 20 years. There’s also a period in its orbit when it’s actually closer to the sun than Neptune because of its shape. 

“Pluto’s orbit is very elliptical and Neptune is less so,” says Weigel.

Another interesting fact about Pluto is that it has a large number of moons. In all, it has five of them: Charon, which is about half of its size, as well as Nix, Hydra, Kerberos, and Styx. Think underworld theme.

Charon is the largest of Pluto’s moons. Charon and Pluto are so similar in size, in fact, that Weigel says instead of one orbiting the other, “they’re basically dancing with each other in space.” Two of the moons were discovered when New Horizons was on its way to orbit Pluto, and all of them are a good bit smaller than Charon. They’re also angular and not as spherical as Charon.

Thanks to New Horizons, we finally have a real picture of Pluto. Our best observations from Hubble could only show us a slight variation in color before, but now we know what its surface looks like and how thin its atmosphere is. We know its temperature and how it orbits.

“Mostly everything we’ve discovered about Pluto is thanks to New Horizons,” says Weigel.

Read More: Pluto May Have Formed From the Newly Discovered Kiss and Capture Mechanism

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• NASA. Pluto Facts

• NASA. New Horizons

• NASA. Moons of Pluto

Sara Novak is a science journalist based in South Carolina. In addition to writing for Discover, her work appears in Scientific American, Popular Science, New Scientist, Sierra Magazine, Astronomy Magazine, and many more. She graduated with a bachelor’s degree in Journalism from the Grady School of Journalism at the University of Georgia. She's also a candidate for a master’s degree in science writing from Johns Hopkins University (expected graduation 2023).