If you're not that into astronomy and the most you paid attention to space was watching Matt Damon in The Martian, NASA's New Horizons Pluto mission may have flown under your radar, so to speak. But actually, the amazing New Horizons discoveries about Pluto - which began beaming back to Earth in mid-2015 - took the scientific world by storm. The project began in the late 1980s as scientists lobbied to discover more about Pluto, but four missions were rejected. Even Bill Nye the Science Guy lobbied for a NASA Pluto mission. Although this project took some time to get off the ground, scientists finally convinced NASA in 2002 to fund the New Horizons mission to explore the farthest regions of space and get a good look at our solar system's smallest and least-known outsider.
NASA's New Horizons mission was launched in 2006 with a probe the size of a grand piano aboard the fastest rocket NASA ever launched – in fact it even carries the ashes of Clyde Tombaugh, the scientist who discovered Pluto. At the time, Pluto was still considered a planet, and two of its moons, Styx and Kerberos, weren’t even discovered yet. Scientists assumed they would just be observing an old gray rock out in the outer region known as the Kuiper Belt and in fact Pluto was demoted to “dwarf planet” months after the New Horizon probe launch. Nine years later, as New Horizons reveals these cool Pluto discoveries (and despite protests), it remains demoted. That doesn't mean, however, that the NASA Pluto discoveries aren't as awesome as it gets.
So, what did New Horizons discover? From ice volcanoes to still evolving geology, vote up the coolest Pluto discoveries New Horizons has sent back to NASA!
Pluto Shouldn't Have An Atmosphere, But It Does
Because Pluto is so small, it doesn't have enough gravity to keep nitrogen particles from being blown away by the sun's ultraviolet rays. The dwarf planet has been around for four billion years, and any atmosphere it had should have dissipated after around 10 thousand years. It's thought that an internal heat source, likely radioactive, has been replenishing Pluto's nitrogen. The nitrogen-rich atmosphere also extends much higher than Earth's, at some 1,000 miles and creates a twilight effect.
Charon's Canyon Is Massive Beyond Belief
The huge chasm that spans Charon's surface is 1,000 miles long and some two miles deep in places, making it four times as long and about twice as deep as Arizona's Grand Canyon. New Horizons could not photograph Charon's other side, but the chasm may extend around the moon.
Pluto Has A Blue Sky
The first color images New Horizons sent back incredibly revealed this blue ring around the plutoid, which scientists hardly expected. While the haze isn't truly "blue," (more likely the particles are red and gray), it looks that color due to the way they reflect sunlight. This tells the scientists there is a molecular process taking place in Pluto's atmosphere similar to that of Earth and Saturn.
Pluto's Largest Moon May Once Have Had Water, Too
Charon, half Pluto's diameter, is turning out to be almost as fascinating as Pluto itself. Rather than being essentially a crater-battered rock out in the Kuiper Belt, New Horizon photos reveal it to have a violent history reflected in canyons, mountain ranges and fractured regions. It may even once have had an underground water system that turned into ice and cracked the surface wide open.