Back in the olden days of 1979 I took an undergraduate course in astronomy at the University of Washington. The Voyager spacecraft had just visited Jupiter and the astronomy faculty were positively giddy about the new photos, data, and knowledge coming in from the largest planet in our solar system. The excitement is perhaps even greater as we digest the first images from New Horizons, which buzzed Pluto earlier this week and got our first really close look at what used to be the ninth planet.
“It’s discovering a new planet that we already knew existed,” said Brett Morris, a UW graduate student in astronomy, at a special Pluto-palooza version of Astronomy on Tap Seattle Wednesday evening at Bad Jimmy’s Brewing Company in Ballard.
Morris said the biggest discovery in the first batch of close-ups of Pluto is that, in a section of the dwarf planet’s “heart,” now named “Tombaugh Regio” after its discoverer, Clyde Tombaugh, there are no craters.
“This suggests that the surface is less than 100 million years old,” Morris said. While that may seem like a long time, it’s a mere blink of an eye astronomically and geologically.
“This is really young, and that was a huge surprise,” Morris said. “This is the biggest surprise of the day. The surface must be active.” He added that we have no idea yet how this could be happening, and that scientists didn’t expect to find such a thing.
Another interesting finding were tall mountains in that photo.
“We believe that these mountains are water-ice mountains eleven thousand feet tall,” Morris said, explaining that ice of methane or carbon monoxide would crumble at that height, but that water ice, in a place as cold as Pluto, would be as hard as rock.
“Imagine an ice cube the size of Mt. Rainier,” Morris said. “That’s what we’re looking at.”
Pluto’s largest moon, Charon, has material at its north pole that is darker than the rest of its surface which, like Pluto’s, also appears to be active. They’ve also spotted a large canyon on Charon.
“That canyon is twice as deep as the Grand Canyon, it stretches across a significant chunk of Charon,” Morris explained. “It’s either a really big crater or a valley carved out by something.”
The small moon Hydra appears to be made entirely of ice.
“This is a 30-mile hunk of ice sitting out there orbiting Pluto,” Morris said.
The photos returned by New Horizons are far better than any images of Pluto captured by the Hubble Space Telescope.
“The Hubble Space Telescope tried really hard to give us good images of Pluto, but that’s really difficult because it’s so far away,” Morris said. The telescope was able to see bright and dark regions on Pluto, but that was about it. Hubble also was used to search the Pluto system for rings, moons, and other objects that could be a hazard to the speeding spacecraft.
“At 15 kilometers a second, if there’s a piece of rice in your way it will destroy your spacecraft,” Morris noted. Four of Pluto’s five known moons were discovered by Hubble during this process.
Morris noted that it’s going to take a while for New Horizons to send us all the data it has collected during its flyby of Pluto. The spacecraft is equipped with what he says is essentially a 200-megabyte modem that only contacts Earth every once in a while.
“This is worse than AOL!” he quipped. We should keep receiving photos and data from New Horizons through November of 2016, so we have a lot of cool new discoveries to look forward to. May we be fortunate enough to enjoy a cold brew with each one of them!