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NASA's New Horizons Mission Flies by Pluto

Last Updated: Oct. 11, 2024
Pluto is shown in splotches of red, tan, blue, and yellow surrounding a central heart-shaped tan region.
NASA's New Horizons spacecraft captured this high-resolution enhanced color view of Pluto on July 14, 2015. The image combines blue, red and infrared images taken by the Ralph/Multispectral Visual Imaging Camera (MVIC). Many landforms have their own distinct colors, telling a complex geological and climatological story that scientists have only just begun to decode. › Full image and caption.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Pluto's moon Charon

Remarkable new details of Pluto’s largest moon Charon are revealed in this image from New Horizons’ Long Range Reconnaissance Imager (LORRI), taken late on July 13, 2015 from a distance of 289,000 miles  (466,000 kilometers). Full image and caption.

In the News

We visited Pluto!

On July 14, 2015 at 4:49 a.m. PDT, NASA's New Horizons spacecraft sped past Pluto – a destination that took nearly nine and a half years to reach – and collected scientific data along with images of the dwarf planet.

Pluto, famous for once being the ninth planet, was reclassified as a dwarf planet in 2006 after new information emerged about the outer reaches of our solar system. Worlds similar to Pluto were discovered in the region of our solar system known as the Kuiper Belt. The Kuiper Belt – named for astronomer Gerard Kuiper – is a doughnut-shaped area beyond the orbit of Neptune that is home to Pluto, other dwarf planets such as Eris, Makemake, and Haumaea, as well as hundreds of thousands of other large icy bodies, and perhaps trillions of comets orbiting our sun. Over the next several years, the New Horizons spacecraft is expected to visit one to two more Kuiper Belt objects.

Even though it will take 16 months for New Horizons to return all the Pluto science data to Earth, we have already made some interesting and important discoveries about Pluto.

This animation zooms into the base of the heart-shaped feature on Pluto to highlight a new image captured by NASA's New Horizons. The new image, seen in black and white against a previously released color image of Pluto, shows a mountain range with peaks jutting as high as 11,000 feet (3,500 meters) above the surface of the icy body. Credit: NASA/JHUAPL/SwRI

Why It's Important

Through careful measurements of new images, scientists have determined that Pluto is actually larger than previously thought: 2,370 kilometers in diameter. This is important information for scientists because it helps them understand the composition of Pluto. Because of the orbital interactions between Pluto and its moon Charon, Pluto’s mass is well known and understood. Having a more precise diameter gives scientists the ability to more accurately calculate the average density. A greater diameter means Pluto’s density is less than we thought.

Images of Pluto start as a blob of white pixels that become more colorful and clear as the animation progresses, ending in a crisp overhead view of a portion of the surface.

This animation combines various observations of Pluto over the course of several decades. The first frame is a digital zoom-in on Pluto as it appeared upon its discovery by Clyde Tombaugh in 1930 (image courtesy Lowell Observatory Archives). The other images show various views of Pluto as seen by NASA's Hubble Space Telescope beginning in the 1990s and NASA's New Horizons spacecraft in 2015. The final sequence zooms in to a close-up frame of Pluto released on July 15, 2015. | Full image and caption.

If you do the math, you’ll see that Pluto’s calculated density dropped from 2,051 kg/m3 to 1,879 kg/m3 with this new finding. Most rock has a density between 2000-3000 kg/m3 and ice at very cold temperatures has a density of 927 kg/m3, so we can conclude that Pluto is a bit more icy than previously believed. In addition to helping scientists calculate the density of Pluto, this measurement confirms Pluto as the largest known object in the Kuiper Belt.

Pluto and Charon are superimposed over an image of Earth.

This graphic presents a view of Pluto and Charon as they would appear if placed slightly above Earth's surface and viewed from a great distance. Recent measurements obtained by New Horizons indicate that Pluto has a diameter of 2370 km, 18.5% that of Earth's, while Charon has a diameter of 1208 km, 9.5% that of Earth's. | Full image and caption.

Teach It

We’ve provided some math problems (and answers) for you to use in the classroom. They’re a great way to provide students with real-world examples of how the math they’re learning in class is used by scientists. There are also some additional resources below that you can use to integrate the Pluto flyby into your lessons, or use the flyby as a lesson opener!

Pluto Math Problems

  1. Find the radius(r) of Pluto. 2,370 kilometers ÷ 2 = 1,185 km
  2. Find the circumference of Pluto. C = 2 π r = 7,446 km
  3. Find the surface area of Pluto. SA = 4 π r2 = 17,646,012 km2
  4. Find the volume of Pluto. 4/3 π r3 = 6,970,174,651 km3
  5. Find the density of Pluto in kg/m3. mass/volume Pluto mass = 1.31 × 1022kg Convert volume in km3 to m3: 6,970,174,651 × 1,000,000,000 = 6.970174651 × 1018m3 1.31 × 1022kg / 6.970174651 × 1018m3 = 1,879 kg/m3
  6. How does this new density calculation compare to the previous calculation (2051 kg/m3) when Pluto’s diameter was thought to be 2,302 km?

Explore More

Take a look at some of the lessons, videos, activities and interactives related to Pluto. They’re a great way to engage students in STEM and learning more about their solar system!

About the Author

Lyle Tavernier

Educational Technology Specialist, NASA-JPL Education Office

Lyle Tavernier is an educational technology specialist at NASA's Jet Propulsion Laboratory. When he’s not busy working in the areas of distance learning and instructional technology, you might find him running with his dog, cooking or planning his next trip.