Investigative Reports

Pluto Up Close: What New Horizons’ Images Revealed

By Ivan Petricevic

Published May 13, 2020 4 min read 247 reads

An image of Pluto’s majestic mountains, frozen plains and foggy hazes. This image was taken around 15 minutes after New Horizon's closest approach to Pluto in 2015. Image Credit: New Horizons / NASA/JHUAPL/SwRI.

What did NASA’s New Horizons spacecraft reveal at Pluto? Before the 2015 flyby, Pluto was a distant world seen mostly as a changing point of light. New Horizons showed a complex landscape with nitrogen ice, water-ice mountains, layered haze, dark terrain and a heart-shaped basin larger than many countries.

The spacecraft passed Pluto at high speed, so it could not watch the surface through a full season. Its cameras and instruments collected a geological snapshot: enough detail to transform the science, but not enough to answer every question about how the surface changes over time.

Sputnik Planitia and Pluto’s famous heart

The western lobe of Pluto’s bright heart is Sputnik Planitia, a broad basin filled with nitrogen ice. Its surface is divided into polygon-shaped cells that appear to move slowly as the ice convects. This is not water ice behaving like a glacier on Earth. At Pluto’s temperatures, nitrogen can freeze, flow and sublimate while the harder water ice forms mountain-sized blocks around it.

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Mountains made of water ice

Pluto’s mountains rise several kilometres above the surrounding terrain. Water ice is strong enough at Pluto’s temperatures to act as bedrock, so the mountains can remain stable where they would not survive as ordinary water-ice hills on Earth. Some ridges and pits suggest that the surface has been shaped by freezing, evaporation and the slow movement of volatile ices.

A thin atmosphere and layered haze

New Horizons photographed blue atmospheric haze around Pluto. The haze forms high above the surface when sunlight drives chemical reactions in the atmosphere, producing complex organic particles that settle slowly downward. The colour is not proof that Pluto has an Earth-like sky; it is a clue to chemistry taking place in a very thin atmosphere.

Charon and the other moons

The encounter also revealed detail on Charon, Pluto’s largest moon, including a huge canyon system and a reddish polar region. The smaller moons were not just anonymous points. Their shapes, spins and surfaces added evidence that the Pluto system formed through a violent collision early in Solar System history.

Why the images still matter

The pictures are compelling because they show a world that is neither a frozen rock nor a miniature Earth. Pluto has weather, geology and a surface that changes as sunlight and internal heat work through different materials. NASA’s New Horizons archive remains the starting point for understanding those images, while new analyses continue to test how the terrain formed.

Further reading: NASA New Horizons mission; NASA Solar System Exploration, New Horizons in depth.

Images and surviving evidence

An infograph about dwarf planet Pluto. Shutterstock. — An infographic about dwarf planet Pluto. Shutterstock.

A high-resolution image taken by the New Horizons spacecraft showing Pluto's thin atmosphere. Image Credit: New Horizons. — A high-resolution image taken by the New Horizons spacecraft showing Pluto’s thin atmosphere. Image Credit: New Horizons.

A view of Pluto's Moon Charon, captured by NASA's New Horizons Spacecraft. Image Credit: new Horizons. — A view of Pluto’s Moon Charon, captured by NASA’s New Horizons Spacecraft. Image Credit: New Horizons.

Pluto's Big Heart in Color. This Image was taken on July 13, 2015 at a distance of 476,000 miles (768,000 Kilometers) from the surface. Shutterstock. — Pluto’s Big Heart in Color. This image was taken on July 13, 2015, at a distance of 476,000 miles (768,000 kilometers) from the surface. Shutterstock.

A close-up image of the dunes on Pluto's surface. Image Credit: New horizon's Spacecraft. — A close-up image of the dunes on Pluto’s surface. Image Credit: New horizon’s Spacecraft.

An image of haze layers above Pluto’s limb taken by the Ralph/Multispectral Visible Imaging Camera (MVIC). Image Credit: New Horizons.

An image of the bladed terrain of Pluto’s informally named Tartarus Dorsa region, imaged by NASA’s New Horizons spacecraft in July 2015. Image Credit: New Horizons.

A New Horizon image of Floating Hills on Pluto's Sputnik Planum. Image Credit: New Horizons. — A New Horizon image of Floating Hills on Pluto’s Sputnik Planum. Image Credit: New Horizons.

An image of Pluto’s Wright Mons in color. It shows of one of two potential cryovolcanoes spotted on the surface of Pluto by the New Horizons spacecraft in July 2015. Image Credit: New Horizons. — An image of Pluto’s Wright Mons in color. It shows one of two potential cryovolcanoes spotted on Pluto’s surface by the New Horizons spacecraft in July 2015. Image Credit: New Horizons.

This is one of the sharpest images to date of Pluto’s weird landscape, revealed surface details to a scale of 270 meters. Image Credit: New Horizons.

An elevation map of Pluto's sunken heart. Seen in the image are angular blocks of water ice located along the western edge of the so-called Sputnik Planitium are seen "floating" in the bright deposits of much softer, denser solid nitrogen. Image Credit: New Horizon's Spacecraft. — An elevation map of Pluto’s sunken heart. Seen in the image, are angular blocks of water ice located along the western edge of the so-called Sputnik Planitium are seen “floating” in the bright deposits of much softer, denser solid nitrogen. Image Credit: New Horizon’s Spacecraft.

Extensional faults (arrows) on the surface of Pluto indicate expansion of the dwarf planet’s icy crust, attributed to freezing of a subsurface ocean. (Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Alex Parker). — Extensional faults (arrows) on Pluto’s surface indicate expansion of the dwarf planet’s icy crust, attributed to the freezing of a subsurface ocean. (Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Alex Parker).

Author profile

Ivan Petricevic

Ivan Petricevic is an investigative journalist and researcher with more than a decade of experience covering ancient history, UAP phenomena, space, and science. He writes about space, science, and history for Večernji list and has appeared as an expert on Discovery Channel and History Channel. He founded Curiosmos, where he reports from primary sources, archaeological research, and field investigations.

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