Standing in a hallway decorated with images of planets and other space objects, John Spencer is looking at a high resolution photo of Pluto hanging in front of him. It’s striking, a mostly gray sphere with dark maroon and golden hues. Spencer, a planetary scientist with the Southwest Research Institute’s who works out of their Boulder office, points out features.
"The North Pole is up here. This area up here is a vast plain of frozen nitrogen."
It’s hard to believe, but until July 2015, scientists like Spencer had almost no idea what Pluto looked like. That’s when the New Horizons spacecraft zoomed by the dwarf planet, capturing images and data that led to a vast reimagining of Pluto. Now, he and others are sharing what they’ve learned.
As he guides a viewer through the image, Spencer points out geological features, like topographical relief rising on the outskirts of a vast glacier of frozen nitrogen.
"These are mountains the size of the Rockies that ring the edge, that look like these icebergs floating in the nitrogen ice."
All this new knowledge - about the planet’s geology, atmosphere, moons and other features are being released in five papers published in the journal Science. Spencer, who has studied Pluto and several other planets, is a font of details now. Yet prior to the New Horizons flyby, the image he and other scientists had of Pluto was pretty hazy.
"We had these pictures from the Hubble Telescope that were these fuzzy blobs and you could maybe make out some darker or lighter areas," he said.
That’s because Pluto is so far away from Earth. It took New Horizons, traveling at a speed of around 10 miles a second, nine years to get to Pluto. It got to Jupiter by the 13 month mark, took pictures of that planet, and then took eight more years to get to Pluto.
"So yeah, Jupiter’s just in our backyard by the standards of Pluto," Spencer said, laughing.
Some of the new findings focus on the odd geology of Pluto, said Spencer. Like that giant glacier of frozen nitrogen that’s hundreds of miles across. On Earth, nitrogen gas is what makes up most of our atmosphere. On frigid Pluto's surface, at times it's in solid form.
The scientists were surprised at just how young some of the geology was on the planet; they expected scarring from historic collisions with planetary debris. They didn’t expect so many smoother parts, indicating those scars are being eroded and ground down by recent geologic activity.
"Pluto is a living world geologically, with a lot going on there," said Spencer.
Spencer also said what we learn about Pluto helps us understand more about Earth. Every time we visit a new place in the solar system that teaches us more about planets in general, he said.
"And that feeds back into understanding the planet we care most about, our own planet."
New Horizons is well past Pluto now, but its mission isn’t complete. Spencer and other scientists are planning to fly it past what’s called the Kuiper Belt -- a field of comets, dwarf planets and other objects. They hope flying by one of these objects in 2019 can help them learn more about the creation of our solar system.
Then after that, New Horizons will continue its journey out into the galaxy. It’s flying so fast the sun’s gravity can’t slow it down too much. The spacecraft is expected to continue communicating with Earth periodically, sending back information about the solar system, until some time in 2030, when its radio transmitter is expected to run out of power.
