Cable news channels have been airing the latest images from Pluto all week. Twitter is filled with #PlutoFlyby musings. Popular brands have photoshopped themselves onto the far-away dwarf planet to get a piece of the action.
And yet, the giddiest and most awestruck observers may be the NASA scientists in charge of the mission.
"I don't think any one of us could have imagined that it was this kind of a toy store," said Alan Stern, the mission's principal investigator. He spoke at a NASA press conference, held at Johns Hopkins University's Applied Physics Laboratory, where the mission team unveiled new images and the initial insights they provoked.
The New Horizons spacecraft has sent back initial high-resolution photos of the dwarf planet Pluto and its moon Charon. The detail they provide has already transformed scientific understanding of what's happening on the orb 3 billion miles away.
For one, Pluto has virtually no craters. Pluto and Charon should be pockmarked, like the Earth's moon. They sit at the edge of the solar system, near the Kuiper Belt, which is filled with rocks, ices, and other materials left over from the formation of the solar system. By contrast, a smooth surface is one that's been refreshed, somewhat recently, and perhaps continuously.
And that means that Pluto is a geologically active planet.
There are also 11,000-foot mountains of water-ice, another sign of internal activity. Scientists have seen volcanism on the moons of large gas planets, such as Saturn and Jupiter. That makes more sense. The gravity of a giant planet mashes the little moons from the inside out, which is why Jupiter's Europa and Io show volcanic activity. Pluto has no giant neighbor. The planet generates heat on its own, and from these first images, the scientists can't say why—possibly the presence of radioactive elements. It's Pluto's first lesson: You can have activity on a planet that has no giant neighbor. That sounds arcane, but to hear these scientists talk about it, you'd have thought someone had given each of them a pony.
Pluto isn't the only story. "Charon blew our socks off," says Cathy Olkin, a team member who works at the Southwest Research Institute in Colorado. The moon offers an amount of geologic variety that surprised the team, including valleys, cliffs, and a foreboding reddish region at its northern pole. "Informally, we've been referring to that as Mordor," Olkin says, nodding to the land of doom in The Lord of the Rings trilogy.
The press conference wasn't all science. The team struck a sentimental note when they announced that a heart-shaped formation on Pluto, first visible to New Horizons from 70 million miles away, wouldn't be known as Pluto's heart anymore. They informally renamed it Tombaugh Reggio, after the man who discovered the planet, Clyde Tombaugh, and whose ashes—aboard New Horizons—are currently headed out of the solar system.