An Atlas V rocket carrying the New Horizons spacecraft on a mission to the planet Pluto lifts off from launch pad 41 at the Cape Canaveral Air Force Station in Florida on January 19, 2006. #

Clyde Tombaugh, the amateur astronomer who discovered Pluto on February 18, 1930, pictured in 1931. Tombaugh was working as a researcher for the Lowell Observatory in Flagstaff, Arizona, searching for a predicted “Planet X,” when he made the discovery by comparing photographic plates made of star fields over the course of several nights. #

In 2003, this was the most detailed image of the surface of Pluto available, as constructed from multiple photographs taken by NASA’s Hubble Space Telescope from 2002 to 2003. #

An aluminum canister containing the ashes of Clyde Tombaugh, the American astronomer who discovered Pluto in 1930, attached to NASA's New Horizons spacecraft. Tombaugh passed away in 1997 at the age of 90. On Tuesday, July 14, 2015, the spacecraft is scheduled to pass within 7,800 miles of Pluto, which he discovered 85 years ago. #

Members of the media garbed in protective uniforms view NASA's New Horizons spacecraft on November 4, 2005, in the Payload Hazardous Servicing Facility at Kennedy Space Center. #

A 2004 Florida quarter is prepared for installation on the New Horizons spacecraft in Kennedy Space Center's Payload Hazardous Servicing Facility on December 7, 2005. The new quarter, engraved with the "Gateway to Discovery" design, will accompany New Horizons on its 3-billion-mile journey to the dwarf planet Pluto and its moon, Charon. Although appropriate for the mission to carry the coin from the state that symbolizes space exploration, it will also serve a practical purpose: Scientists are using the quarter as a spin-balance weight. #

Patricia Tombaugh, 92,  of Las Cruces, New Mexico, stands next to a model of the New Horizons spacecraft at the Kennedy Space Center on January 15, 2006. Her late husband, Clyde Tombaugh discovered the dwarf planet Pluto in 1930. #

In the Payload Hazardous Servicing Facility at the John F. Kennedy Space Center in Florida, two fairing sections move into place around the New Horizons spacecraft for encapsulation on December 13, 2005. The fairing protects the spacecraft during launch and flight through the atmosphere. Once out of the atmosphere, the fairing is jettisoned. #

A white arrow marks Pluto in this New Horizons Long Range Reconnaissance Imager (LORRI) picture taken on September 21, 2006. Seen at a distance of about 4.2 billion kilometers (2.6 billion miles) from the spacecraft, Pluto is little more than a faint point of light among a dense field of stars. Mission scientists knew they had Pluto in their sights when LORRI detected an unresolved “point” in Pluto's predicted position, moving at the planet's expected motion across the constellation of Sagittarius near the plane of the Milky Way galaxy. #

Pluto's moons Hydra and Nix were first spotted by the Hubble Space Telescope in 2005. This follow-up image helped confirm the discovery. The confirmation reinforces the emerging view that the Kuiper Belt, a swarm of icy bodies encircling the solar system beyond Neptune, may be more complex and dynamic than astronomers once thought. The moons' orbits are in the same plane as the orbit of the much larger satellite Charon (discovered in 1978). This likely means the moons were not captured, but instead were born, along with Charon, in what is commonly theorized to have been a titanic collision between two Pluto-sized objects over 4 billion years ago. Astronomers believe that the formation of the Pluto system is similar to that of our Earth and Moon. In both cases a comparable-sized body slammed into the parent planet. Simulations show that debris from the collision would go into an orbit around the planet and coalesce to form one or more satellites. #

The New Horizons Long Range Reconnaissance Imager took this 4-millisecond exposure of Jupiter and two of its moons on January 17, 2007. The spacecraft was 42.5 million miles (68.5 million kilometers) from Jupiter, closing in on the giant planet at 41,500 miles (66,790 kilometers) per hour. The volcanic moon Io is the closest moon to the right of Jupiter; the icy moon Ganymede is to Io's right. The shadows of each satellite are visible atop Jupiter's clouds; Ganymede's shadow is draped over Jupiter's northwestern limb. #

This beautiful image of the crescents of volcanic Io and more sedate Europa is a combination of two New Horizons images taken on March 2, 2007, about two days after New Horizons made its closest approach to Jupiter. This image was taken from a range of 2.8 million miles (4.6 million kilometers)  from Io and 2.4 million miles (3.8 million kilometers) from Europa. Although the moons appear close together in this view, a gulf of 490,000 miles (790,000 kilometers) separates them. Io’s night side is lit up by light reflected from Jupiter, which is off the frame to the right. Europa's night side is dark, in contrast to Io, because this side of Europa faces away from Jupiter. Here Io steals the show with its beautiful display of volcanic activity. Three volcanic plumes are visible. Most conspicuous is the enormous 190-mile- (300-kilometer-) high plume from the Tvashtar volcano at the 11 o'clock position on Io’s disk. Two much smaller plumes are also visible: that from the volcano Prometheus, at the 9 o'clock position, and from the volcano Amirani, seen between Prometheus and Tvashtar. The Tvashtar plume appears blue because of the scattering of light by tiny dust particles ejected by the volcanoes, similar to the blue appearance of smoke. #

The New Horizons Multispectral Visible Imaging Camera (MVIC) snapped this incredibly detailed picture of Jupiter's high-altitude clouds on February 28, 2007, when the spacecraft was only 1.4 million miles (2.3 million kilometers) from the solar system's largest planet. #

This five-frame sequence of New Horizons images captured the giant plume from Io's Tvashtar volcano on March 1, 2007, at a distance of 2.4 million miles (3.8 million kilometers). #

New Horizons took this image of the icy moon Europa rising above Jupiter’s cloud tops after the spacecraft’s closest approach to Jupiter. The spacecraft was 1.4 million miles (2.3 million kilometers) from Jupiter and 1.8 million miles (3 million kilometers) from Europa when the picture was taken. #

This image, taken by the Hubble Space Telescope, shows five moons orbiting the distant, icy dwarf planet Pluto. The circle marks the newly discovered moon, designated S/2012 (134340) 1, or P5, as photographed by Hubble’s Wide Field Camera 3 on July 7, 2012. The moon is estimated to be approximately 6 to 16 miles (10 to 25 kilometers) across, in a 59-000-mile (95,000-kilometer) diameter circular orbit around Pluto that is assumed to be aligned in the same plane as the other satellites in the system. The darker stripe in the center of the image is because the picture is constructed from a long exposure—designed to capture the comparatively faint satellites of Nix, Hydra, P4, and S/2012 (134340) 1—and a shorter exposure designed to capture Pluto and Charon, which are much brighter. #

An April 9, 2015 picture of Pluto and its largest moon, Charon, taken by the Ralph color imager aboard NASA’s New Horizons spacecraft. It was the first color image ever made of the Pluto system by a spacecraft on approach, according to NASA. The image was made from a distance of about 71 million miles (115 million kilometers), roughly the distance from the Sun to Venus. #

The first color movie from NASA's New Horizons mission showed Pluto and its largest moon, Charon, in their complex orbital dance. This near-true color movie was assembled from images made in three colors—blue, red and near-infrared—by the Multicolor Visible Imaging Camera on the instrument known as Ralph. The images were taken on nine different occasions from May 29 to June 3, 2015. The movie is barycentric, meaning that both Pluto and Charon are shown in motion around the binary's barycenter—the shared center of gravity between the two bodies as they do a planetary jig. Because Pluto is much more massive than Charon, the barycenter (marked by a small “x” in the movie) is much closer to Pluto than to Charon. #

This image, taken by New Horizons’ Long Range Reconnaissance Imager (LORRI), shows numerous large-scale features on Pluto's surface as the spacecraft approached in early 2015. #

In the New Horizons Mission Operations Center at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, flight controllers (from left) Chris Regan and Becca Sepan monitor data from NASA’s New Horizons spacecraft on June 30, after a short course-correction maneuver refined New Horizons’ path toward a flyby of Pluto on July 14. #

New Horizons was about 3.7 million miles (6 million kilometers) from Pluto and Charon when it snapped this portrait late on July 8, 2015. Color information from previous observations was added to this image. #

This color version of a New Horizons Long Range Reconnaissance Imager (LORRI) picture of Pluto taken July 3, 2015, was created by adding color data from the Ralph instrument gathered earlier in the mission. The LORRI image was taken from a range of 7.8 million miles (12.5 million kilometers.) #

A portrait from the final approach. Pluto and Charon display striking color and brightness contrast in this composite image from July 11, 2015, showing high-resolution black-and-white LORRI images colorized with Ralph data collected from the last rotation of Pluto. #

Charon’s newly discovered system of chasms, larger than the Grand Canyon on Earth, rotates out of view in New Horizons’ sharpest image yet of the Texas-sized moon. It’s trailed by a large equatorial impact crater that is ringed by bright rays of ejected material. In this latest image, the dark north polar region is displaying new and intriguing patterns. This image was taken on July 12 from a distance of 1.6 million miles (2.5 million kilometers). #

Pluto’s bright, mysterious “heart” is rotating into view, ready for its close-up on close approach, in this image taken by New Horizons on July 12 from a distance of 1.6 million miles (2.5 million kilometers). It is the target of the highest-resolution images that will be taken during the spacecraft’s closest approach to Pluto on July 14. The intriguing “bulls-eye” feature at right is rotating out of view, and will not be seen in greater detail. #

Members of the New Horizons science team react to seeing the spacecraft's last and sharpest image of Pluto before closest approach later in the day at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, on July 14, 2015. #

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). A swath of cliffs and troughs stretches about 600 miles (1,000 kilometers) from left to right, suggesting widespread fracturing of Charon’s crust, likely a result of internal processes. At upper right, along the moon’s curving edge, is a canyon estimated to be 4 to 6 miles (7 to 9 kilometers) deep. Mission scientists are surprised by the apparent lack of craters on Charon. South of the moon’s equator, at the bottom of this image, terrain is lit by the slanting rays of the sun, creating shadows that make it easier to distinguish topography. Even here, however, relatively few craters are visible, indicating a relatively young surface that has been reshaped by geologic activity. In Charon’s north polar region, a dark marking prominent in New Horizons’ approach images is now seen to have a diffuse boundary, suggesting it is a thin deposit of dark material. Underlying it is a distinct, sharply bounded, angular feature; higher resolution images still to come are expected to shed more light on this enigmatic region. The image has been compressed to reduce its file size for transmission to Earth. In high-contrast areas of the image, features as small as 3 miles (5 kilometers) across can be seen. Some lower-contrast detail is obscured by the compression of the image, which may make some areas appear smoother than they really are. The uncompressed version still resides in New Horizons’ computer memory and is scheduled to be transmitted at a later date. #

New close-up images of a region near Pluto’s equator reveal a giant surprise: a range of youthful mountains rising as high as 11,000 feet (3,500 meters) above the surface of the icy body. The mountains likely formed no more than 100 million years ago -- mere youngsters relative to the 4.56-billion-year age of the solar system -- and may still be in the process of building, says Jeff Moore of New Horizons’ Geology, Geophysics and Imaging Team (GGI). That suggests the close-up region, which covers less than one percent of Pluto’s surface, may still be geologically active today. Moore and his colleagues base the youthful age estimate on the lack of craters in this scene. Like the rest of Pluto, this region would presumably have been pummeled by space debris for billions of years and would have once been heavily cratered -- unless recent activity had given the region a facelift, erasing those pockmarks. “This is one of the youngest surfaces we’ve ever seen in the solar system,” says Moore. Unlike the icy moons of giant planets, Pluto cannot be heated by gravitational interactions with a much larger planetary body. Some other process must be generating the mountainous landscape. “This may cause us to rethink what powers geological activity on many other icy worlds,” says GGI deputy team leader John Spencer of the Southwest Research Institute in Boulder, Colorado, The mountains are probably composed of Pluto’s water-ice “bedrock.” Although methane and nitrogen ice covers much of the surface of Pluto, these materials are not strong enough to build the mountains. Instead, a stiffer material, most likely water-ice, created the peaks. “At Pluto’s temperatures, water-ice behaves more like rock,” said deputy GGI lead Bill McKinnon of Washington University, St. Louis. The close-up image was taken about 1.5 hours before New Horizons closest approach to Pluto, when the craft was 478,000 miles (770,000 kilometers) from the surface of the planet. The image easily resolves structures smaller than a mile across. #