New Horizons raced past Pluto on July 14, becoming the first spacecraft from Earth ever to investigate the dwarf planet. Astronomers needed time after the flyby to receive and analyze the raw data from the far-flung observatory.
Pluto revealed a vast icy heart-shaped area for the first time to humans just a few days before close approach. When New Horizons buzzed the distant globe, cameras focused in on this strange heart formation, along with other features on the visible hemisphere of Pluto.
Early analysis suggests the light-colored heart is composed, in part, of a young, craterless plain, believed to be just around 100 million years old. If this is confirmed, then Pluto has experienced significant change in its surface in the relatively recent past, or could even still be geologically alive today.
Astronomers have informally nicknamed the heart Tombaugh Regio, in honor of Clyde Tombaugh, the astronomer who discovered Pluto in 1930. The new terrain, set near the center of the heart, has been dubbed Sputnik Planum, in recognition of the first artificial satellite in space. The photo of this region is being called "the heart of the heart" photograph. It was recorded at a distance of 48,000 miles from the dwarf planet, and the smallest detail visible in the image is around a half-mile in size.
Within the icy plain lie segments of surface material averaging 12 miles from side to side. These pieces are separated by shallow troughs of darker material, images suggest. These could be the result of material rising up from below like wax in a lava light, or could be formed through contraction, like fields of dried mud on Earth.
By July 18, the spacecraft was already racing away from the distant dwarf planet, covering millions of miles in just four days.
3,080,200 miles / 4957101km from Pluto. This is our last chance to get data from the encounter hemisphere. Go instruments! #PlutoFlyby
— NASA New Horizons (@NASANewHorizons) July 18, 2015
New Horizons spent approximately nine-and-a-half years flying to its primary target. When the vehicle was launched in 2006, Pluto was still considered to be the ninth planet. Just months after New Horizons left our planet, the distant world was reclassified by astronomers as a dwarf planet.
"With the flyby in the rearview mirror, a decade-long journey to Pluto is over - but, the science payoff is only beginning. Data from New Horizons will continue to fuel discovery for years to come," Jim Green, director of Planetary Science at NASA, said.
Video of the flyby of Pluto by the New Horizons spacecraft is available on the NASA YouTube page.