For 85 years after its discovery, Pluto was just a dot. Even the most powerful telescopes humans built — Hubble included — could only show Pluto as a fuzzy blob a few pixels across. To see Pluto properly, somebody was going to have to go there.
The mission to do it was called New Horizons. It is the fastest spacecraft ever launched from Earth, the smallest interplanetary probe NASA has ever flown, and the first — the very first — to ever fly past Pluto.
New Horizons is a NASA spacecraft launched on 19 January 2006 to fly past Pluto. After a 9-year, 5-billion-km journey, it reached Pluto on 14 July 2015, took the first close-up photographs of Pluto and its moons, and then kept flying. In 2019 it visited a smaller object called Arrokoth, deep in the Kuiper Belt — the most distant world ever explored up close.
Launch — January 2006
New Horizons left Earth on 19 January 2006 from Cape Canaveral in Florida. It was the fastest spacecraft ever launched from Earth's surface. To get an idea of how fast: the Apollo astronauts took about three days to reach the Moon. New Horizons crossed the Moon's orbit in just nine hours.
And even at that speed, it would take 9 years and 5 months to reach Pluto. Space is wide.
The Long Cruise — 2006 to 2015
For most of those nine years, New Horizons was asleep. NASA put it into a kind of hibernation mode to save power and reduce wear on the spacecraft's systems. Engineers would wake it up once a year for a few weeks to check the instruments, then put it back to sleep.
In 2007, only a year after launch, New Horizons swung past Jupiter. The giant planet's gravity gave it a "slingshot" boost, throwing it onward toward Pluto even faster. On the way, the spacecraft took beautiful new photographs of Jupiter's storms, rings, and moons — and used the planet as a free speed boost.
14 July 2015 — Mission Control Holds Its Breath
By July 2015, New Horizons was approaching Pluto at 14 km per second, with no chance to slow down. The whole encounter would last only a few hours. And the spacecraft would be busy — taking photographs, measuring the atmosphere, scanning Charon — so it couldn't talk to Earth at the same time.
On the morning of 14 July, the spacecraft went silent on purpose. Mission control would have to wait 9 hours after the flyby before getting a signal back confirming that the spacecraft had survived — because that's how long the signal takes to travel from Pluto to Earth at the speed of light.
Mission control sat in Maryland. Nine years of work. Five billion kilometres of travel. And a spacecraft hurtling past Pluto with no chance to slow down. For nine hours that day, nobody on Earth knew whether New Horizons had survived. Then, on time, the signal came back. Cheering broke out. People cried.
The Closest Approach — 12,500 km Above Pluto
At its closest, New Horizons came within 12,500 km of Pluto's surface — closer to Pluto than the Moon is to Earth. From that vantage point, it took the first sharp photographs ever taken of Pluto and its moons. The very first close-up image showed Pluto's giant heart-shaped feature, bright and clear. More on Pluto's surface.
Sending the Data Home — 16 Months of Downloading
Here is one of the most striking facts of the whole mission. New Horizons captured all of its Pluto data in about a day. But getting that data back to Earth took 16 months. Why? Because Pluto is so far away that radio signals are very weak by the time they reach Earth. New Horizons could only send data home at about 2 kilobits per second — a million times slower than your home Wi-Fi. The full set of Pluto photographs and measurements only finished arriving on Earth in October 2016.
After Pluto — The Arrokoth Flyby
New Horizons didn't stop at Pluto. The mission team picked a new target deep in the Kuiper Belt — a small object called Arrokoth, which means "sky" in the Native American Powhatan language. On 1 January 2019, New Horizons flew past Arrokoth at a distance of just 3,500 km.
Arrokoth turned out to be a strange two-lobed snowman-shaped object, the most distant world ever explored up close by a human-made spacecraft. More on the Kuiper Belt and Arrokoth.
Where Is New Horizons Now?
New Horizons is still travelling outwards through the Kuiper Belt, more than 60 times Earth's distance from the Sun. It is still active, still sending data back home about the outer solar system. It has enough fuel to keep operating until at least the late 2030s. After that, it will keep drifting silently outward, joining the Voyager spacecraft as one of the few human-made objects ever to leave our solar system.
Tucked inside New Horizons is a small metal container holding a portion of Clyde Tombaugh's ashes. Tombaugh discovered Pluto in 1930 and died in 1997. His ashes flew past the world he found in July 2015 and are now drifting beyond the Kuiper Belt — the only human remains ever to leave the solar system. The full story of Tombaugh's discovery.
Launched in 2006.
Slept for nine years.
Arrived at Pluto in 2015.
Still flying.
See the world New Horizons found: Pluto's surface, Pluto's atmosphere, or jump back to the main Pluto facts page.
Frequently Asked Questions
When did New Horizons fly past Pluto?
New Horizons made its closest approach to Pluto on 14 July 2015, after a 9-year, 5-billion-kilometre journey. It came within 12,500 km of Pluto's surface and took the first close-up photographs of the dwarf planet and its moons.
How long did New Horizons take to reach Pluto?
New Horizons took 9 years and 5 months to reach Pluto. It launched on 19 January 2006 and arrived at Pluto on 14 July 2015. Even though it was the fastest spacecraft ever launched from Earth, Pluto is incredibly far away — about 5 billion km from the Sun.
Where is New Horizons now?
New Horizons is still travelling outward through the Kuiper Belt, more than 60 times further from the Sun than Earth. It is still sending data home and has enough fuel to keep operating until at least the late 2030s. After that, it will keep drifting silently outward through space.
Did New Horizons land on Pluto?
No. New Horizons was a flyby mission — it flew past Pluto at 14 km per second without slowing down. It would have used too much fuel to slow down and land. Instead, it captured all its data during a few intense hours as it passed Pluto and its moons.
How long did it take to send the Pluto data back to Earth?
About 16 months. Pluto is so far away that radio signals are very weak by the time they reach Earth. New Horizons could only transmit data at about 2 kilobits per second — a million times slower than home Wi-Fi. The full data set finished arriving in October 2016.