Pluto is small. So small you could fit two of them inside Earth's Moon. But every single fact about Pluto somehow ends up being huge — bigger than you'd expect, weirder than you'd guess, more beautiful than you knew. Here are twenty of the best, organised into four sections so you can find your favourite kind of wow.
Because Pluto is a tiny, faraway, freezing dwarf planet that has somehow accumulated more astonishing details than almost any other world we know. It has a heart of ice, a blue sky, ice volcanoes, five moons named after the underworld, an 11-year-old who named it, and the only human ashes ever to leave the solar system. The whole place is a wow-fact factory.
Size and Distance — The Numbers That Don't Quite Add Up
- Pluto is smaller than Earth's Moon. It is 2,377 km across, compared to the Moon's 3,474 km. You could fit two Plutos inside our Moon with space to spare. → Pluto vs Earth comparison
- Pluto is smaller than seven moons in our solar system. Jupiter's Ganymede, Saturn's Titan, Jupiter's Callisto, Jupiter's Io, our Moon, Jupiter's Europa, and Neptune's Triton are all bigger.
- Pluto's gravity is just 6.3% of Earth's. A 45 kg kid would weigh only 3 kg there — lighter than a small backpack. You could jump six times higher than on Earth.
- It would take 6,293 years to drive from Earth to Pluto at motorway speed. By passenger jet, it'd take about 600 years. NASA's New Horizons did it in 9 years and 5 months.
- Sunlight takes 5 hours to reach Pluto. Whatever Pluto is doing right now, we won't see it for another 5 hours.
Time, Spin and Motion — Pluto's Wild Calendar
- A year on Pluto lasts 248 Earth years. Pluto has only completed about a third of an orbit since it was discovered in 1930. It won't finish that first Pluto-year-since-discovery until 2178.
- Nobody has ever lived a single Pluto year. Nobody ever will. A child born today would need to live to 257 to celebrate their first Pluto birthday.
- A day on Pluto lasts 6.4 Earth days. Sunrise to sunrise is almost a whole school week.
- Pluto spins backwards. The Sun rises in the west and sets in the east. Only Venus and Uranus do the same.
- Pluto sometimes gets closer to the Sun than Neptune. For about 20 years out of every 248, it cuts inside Neptune's orbit. The last time was 1979 to 1999. → Pluto's strange orbit
Surface and Sky — A Frozen World With Surprises
- Pluto has a giant ice heart. The bright heart-shaped region (Tombaugh Regio) is about 1,600 km across — bigger than France. It was named after the man who discovered Pluto. → Pluto's surface
- Pluto's sky is blue. Same reason Earth's sky is blue — tiny haze particles scatter blue light better than other colours.
- Pluto's atmosphere freezes and falls as snow every year. When Pluto reaches the far point of its orbit, the air gets so cold it becomes solid and lands on the ground as nitrogen snow. Then it turns back into gas as Pluto warms. → Pluto's atmosphere
- Pluto has ice volcanoes. Two huge cryovolcanoes called Wright Mons and Piccard Mons erupt slushy water and ammonia instead of hot lava. Wright Mons is 4 km tall.
- Pluto might have a hidden ocean. Scientists believe a slushy ocean of liquid water may exist deep beneath the surface, kept warm by heat from Pluto's rocky core.
People and History — The Human Side of Pluto
- Pluto was found by a farm boy from Kansas. Clyde Tombaugh was 24 years old, hadn't been to university, and had built his own telescopes out of car parts. → Tombaugh's discovery
- Pluto was named by an 11-year-old girl. Venetia Burney suggested the name over breakfast with her grandfather in 1930. The Lowell Observatory loved it — partly because the first two letters, PL, matched Percival Lowell's initials.
- Tombaugh's ashes are now beyond Pluto. A small container of his cremated remains was tucked inside NASA's New Horizons spacecraft. On 14 July 2015 his ashes flew past the world he had discovered. They are the only human remains ever to leave the solar system.
- Pluto stopped being a planet on 24 August 2006. About 400 astronomers met in Prague and voted on a new definition of "planet." Pluto failed the third rule (clearing its orbit) and was reclassified as a dwarf planet. → Why Pluto isn't a planet
- Pluto has five moons, all named after the underworld. Charon, Styx, Nix, Kerberos and Hydra. The whole Pluto system is the Greek underworld in miniature. → Meet all five moons
A 24-year-old farm boy found a dwarf planet smaller than our Moon, named by an 11-year-old girl, ringed by five moons of the underworld, with a heart-shaped plain of frozen nitrogen, a blue sky, ice volcanoes, a possibly slushy ocean below, an atmosphere that freezes once every 248 years, and a year so long that nobody has ever lived a single one of them. That's Pluto.
A heart of ice. Five underworld moons.
A blue sky. Ice volcanoes. A name from breakfast.
Want to test what you remember? → Take the Pluto quiz. Or pick a fact and go deeper: the discovery story, the heart of ice, or jump back to the main Pluto facts page.
Frequently Asked Questions
What is the most amazing fact about Pluto?
Different people will pick different ones, but the most famous is probably that Pluto has a giant heart-shaped region of frozen nitrogen on its surface, called Tombaugh Regio, which is bigger than the country of France. NASA photographed it for the first time in July 2015.
How cold is Pluto?
The average surface temperature on Pluto is −229 °C (−380 °F). It is so cold that the nitrogen in Pluto's atmosphere freezes solid and falls to the ground as snow when Pluto moves far from the Sun. Pluto is one of the coldest places we know in the solar system.
Is there life on Pluto?
As far as we know, no. The surface is too cold, the atmosphere is too thin to breathe, and sunlight is too weak. But scientists think a slushy ocean of liquid water may exist deep below Pluto's surface, kept warm by heat from its rocky core. If the ocean exists, it could in theory support microbial life.
How long would it take to get to Pluto?
By car at motorway speeds, about 6,293 years. By passenger jet, around 600 years. NASA's New Horizons spacecraft, the fastest ever launched from Earth, took 9 years and 5 months to reach Pluto, arriving on 14 July 2015.
Whose ashes are on Pluto?
A small container holding a portion of Clyde Tombaugh's ashes was placed inside NASA's New Horizons spacecraft before launch. Tombaugh discovered Pluto in 1930 and died in 1997. His ashes flew past Pluto on 14 July 2015 and are now drifting beyond the Kuiper Belt — the only human remains ever to leave the solar system.