And in all the time since astronomers first spotted Pluto in 1930, our little frozen world hasn't even completed one full year. Welcome to Pluto's clock and calendar — the strangest in the solar system. The main Pluto facts page has the headlines.
A day on Pluto lasts about 6.4 Earth days, or 153 hours. That is the time Pluto takes to spin around once. It's much slower than a day on Earth, which is 24 hours. Pluto also spins backwards — the Sun rises in the west and sets in the east.
A Day on Pluto Lasts About 6.4 Earth Days
A day is just the time a world takes to spin once around. Earth spins fast: one full turn every 24 hours. Pluto spins slowly: one full turn every 6.4 Earth days, or 153 hours. So if you lived on Pluto, sunrise-to-sunrise would feel endless. Almost a whole school week of dark would pass between one dawn and the next.
And it gets stranger. Pluto spins in the opposite direction from Earth. On our planet, the Sun rises in the east and sets in the west. On Pluto, the Sun rises in the west and sets in the east — like watching the sky run backwards. Astronomers call this retrograde rotation. Only two planets in the solar system do the same thing: Venus and Uranus. Pluto is in odd company.
A Year on Pluto Lasts 248 Earth Years
A year is the time a world takes to travel once all the way around the Sun. Earth takes 365 days. Pluto takes 248 Earth years.
That number is so big it's hard to feel. So try this. Pluto was discovered on 18 February 1930. Almost a hundred years later, Pluto still hasn't completed one full Pluto-year since the day humans first noticed it. It won't finish that first lap until the year 2178. A baby born today won't be alive to see Pluto cross its discovery line. Their grandchildren might, just.
In all the time since Pluto was discovered, it has travelled only about a third of the way around the Sun. The complete Pluto-year-since-discovery won't finish until 2178. Every astronomer who has ever studied Pluto, all the way back to Clyde Tombaugh in 1930, has been watching the same Pluto-year unfold.
Your Pluto Birthday
Because Pluto's year is so long, kids on Earth are practically newborns in Pluto-years. A child celebrating their 9th Earth birthday today is just 0.036 of a Pluto year old. To celebrate their very first Pluto birthday, they would have to live to be 257.
Here are some example ages translated into Pluto-years:
- 1 Earth year old → 0.004 Pluto-years old
- 9 Earth years old → 0.036 Pluto-years old
- 18 Earth years old → 0.073 Pluto-years old
- 80 Earth years old → 0.32 Pluto-years old (still a third of a Pluto year)
🔭 Your Pluto Birthday Calculator
Enter your Earth age to find out how old you are in Pluto-years:
Nobody has ever lived a single Pluto year.
Nobody ever will.
Pluto's Tipped-Over Spin and the Strangest Seasons
Earth is tilted at 23.5 degrees. That tilt is what gives us seasons — summer when our half of the planet is tipped toward the Sun, winter when we're tipped away. Pluto is tilted at 122 degrees. That means Pluto is almost lying on its side as it spins around the Sun, like a top that has fallen over but hasn't stopped turning. Only Uranus shares this trick in our solar system.
Because Pluto is on its side, and because a Pluto year lasts 248 of ours, the seasons there are extreme. A single Pluto season can last more than 60 Earth years. During a summer at the north pole, one quarter of Pluto's surface gets continuous sunlight for decades. The opposite pole stays in continuous darkness for the same length of time. The sun doesn't just set late — it doesn't set at all, for years.
Imagine moving into a house on the day you were born and discovering that the Sun stays up in the sky the whole time you're growing up. It's still up when you finish school. Still up when you go to university. Still up when you start a job, get married, have children, have grandchildren. Then, one ordinary day in your 60s, the Sun finally sets. That's roughly what a Pluto summer feels like. And then the long dark begins.
Pluto's Last Big Date — 1989
Two important moments on Pluto's calendar both happened in the same year. In September 1989, Pluto reached the closest point in its long oval orbit to the Sun — a moment astronomers call perihelion. This was the warmest Pluto had been in 248 years. At about the same time, Pluto also passed an equinox — the moment its tipped-over axis pointed sideways instead of toward or away from the Sun. For a brief Pluto-moment of a few decades, the planet had its most Earth-like weather.
Since then Pluto has been moving slowly back out into the cold and dark. The next time Pluto will be closest to the Sun is around the year 2237. The next equinox is around 2103. If you're 9 years old today, you might be alive to see that one — just.
Between 1985 and 1990, Pluto was close to the Sun, warmly lit, and lined up perfectly with Earth so that Pluto and Charon kept eclipsing each other from our point of view. Astronomers got the best look at Pluto they had ever had. New Horizons launched 16 years after that lucky window closed. The next equinox like 1989 won't happen until 2103.
Pluto's long year is caused by its long, stretched-out orbit → the Orbit spoke explains how it works. Or find out exactly how much you'd weigh on Pluto → the Pluto vs Earth page. Or jump back to the main Pluto facts page.
Frequently Asked Questions
How long is a day on Pluto?
A day on Pluto lasts about 6.4 Earth days, or 153 hours. That is much slower than a day on Earth. Pluto also spins backwards compared with Earth, rotating from east to west like Venus and Uranus.
How long is a year on Pluto?
A year on Pluto lasts about 248 Earth years. That is how long Pluto takes to travel once around the Sun. A child celebrating their 9th birthday today would have to live until they were 257 to celebrate their first Pluto birthday.
Does Pluto cross Neptune's orbit?
Yes. Pluto's orbit is oval-shaped, so for about 20 years out of every 248-year trip around the Sun, Pluto is actually closer to the Sun than Neptune. The last time this happened was 1979 to 1999. The two never collide because Pluto's orbit is tilted.
How long is a season on Pluto?
A single Pluto season can last more than 60 Earth years. Because Pluto's axial tilt is so extreme (122 degrees) and its year is so long (248 Earth years), the Sun can stay up at one pole or down at the other for decades at a time.
Does Pluto spin backwards?
Yes. Pluto rotates in the opposite direction from Earth, so the Sun would rise in the west and set in the east. This is called retrograde rotation. Only Venus and Uranus in our solar system spin the same way.