Section of Pluto discovery plate
Photograph by New Mexico State University Library, Archives And Special Collections
In 1994, this was the best view of Pluto and its moon Charon (right) that the world had ever seen. Taken by the Hubble Space Telescope's Faint Object Camera, the image showed both objects clearly, but little else.
Photograph by Dr. R. Albrecht, ESA ESO Space Telescope European Coordinating Facility, NASA
In 1996, the world got its first look at the surface of Pluto through the Hubble Space Telescope. Taken with the European Space Agency's Faint Object Camera, the image was 100 pixels across and showed intriguing hints of lighter and darker areas.
Photograph by Alan Stern Southwest Research Institute, Marc Buie Lowell Observatory, NASA and ESA
In 2006, Hubble added two small moons to Pluto's lineup: Nix and Hydra (far right). Pluto now has five known moons, including its large companion Charon (right of Pluto), and New Horizons has been looking for more.
Photograph by NASA, Esa, H. Weaver jhu, Apl, A. Stern swri, the HST Pluto Companion Search Team
In 2010, an analysis of Hubble images revealed a mottled world of orange, white, and black. The centre held a mysterious bright spot, prompting NASA to time the New Horizons mission for a better view of the area, now seen as a heart shape.
Photograph by <a href="http://www.nasa.gov/" target="_blank" rel="noopener noreferrer">NASA</a>, <a href="http://www.spacetelescope.org/" target="_blank" rel="noopener noreferrer">ESA</a>, and M. Buie (Southwest Research Institute)
On April 9, 2015, the New Horizons spacecraft took this photograph of Pluto and Charon from a distance of about 71 million miles (115 million kilometres). It was the first colour photo of the Pluto system made by an approaching spacecraft.
Photograph by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
In this series of photos from April 12 to 18, 2015, Pluto and its largest moon, Charon, whirl around one another. The pair are gravitationally bound to one another, and might even swap atmospheric gases.
Photographs by NASA, Johns Hopkins University Applied Physics Laboratory, Southwest Research Institute
This image, taken on July 7, 2015, was an internet sensation thanks to its clear view of a heart-shaped plain 1,200 miles across (2,000 kilometres). It was the first photograph that New Horizons sent home after briefly losing communication on July 4.
Photograph by NASA-JHUAPL-SwRI
Snapped July 8, 2015, this portrait shows the contrasting colours of Pluto (right) and its moon Charon. Pluto is coppery, while Charon is a dull gray—just one reason scientists are surprised by how very different these two little worlds are.
Photograph by NASA-JHUAPL-SwRI
Taken July 9, 2015, this black-and-white view of Pluto shows the "tail" of an immense black whale shape near the equator. Some scientists initially, and informally, dubbed the whale Cthulhu, after H.P. Lovecraft's character: part man, part dragon, part octopus.
Photograph by NASA-JHUAPL-SwRI
On its final approach, New Horizons sent home this image on July 11, 2015. Surface features on Pluto are becoming more obvious at this point, with signs of craters and polygon-shaped regions that invite speculation. What do you see?
Photograph by NASA/JHUAPL/SWRI
On July 11, 2015, New Horizons got its last look before the flyby at the side of Pluto that faces Charon. Taken from 2.5 million miles (4 million kilometers) from Pluto, the photo gives a better look at those polygons.
Photograph by NASA/JHUAPL/SWRI
Pluto's bright heart-shaped plain is rotating into view on the left in this view from New Horizons on July 12, 2015. The "bull's-eye" feature, which may be a large crater, is rotating out of view and will not be visible in images from the closest encounter with Pluto on July 14.
Photograph by NASA/JHUAPL/SWRI
Taken on July 13, 2015, this is the last image New Horizons sent before its July 14 flyby, when it focused on science in lieu of sending data. The "heart" reveals a smooth face, suggesting that ongoing geological processes may keep it wiped clean.
Photograph by NASA/APL/SwRI
A false-colour image of Pluto and Charon exaggerates differences to make features easier to see. Filters on a New Horizons instrument named Ralph reveal areas within the heart-shaped region that vary in colour.
Photograph by NASA/APL/SwRI
The first close-up view of Pluto's surface reveals that mountains of ice rise 11,000 feet (3,500 metres) above its surface.
Photograph by NASA, Jhuapl, SwRI
