When New Horizons executed its flyby of Pluto on July 14th, 2015 at a distance of 47,800 miles (77,000 km), it snapped a series of hi-res, closeup images. The first ever, in fact. The two NASA revealed to us in a Live Stream conference yesterday, one closeup image of Pluto and the other of its moon, Charon, have given reason for the scientists to come up with new theories to how planets form.
PLUTO AND CHARON ARE ACTIVE
The new photos show that both the dwarf planet and its moon Charon have recently been geographically active. From Pluto’s closeup image we can see massive ice mountains, while on Charon we can actually see a canyon so deep you can actually see through the edge of the planet (at about 2 o’clock, roughly 5 miles deep!).
“The most striking thing about this image is, we have not yet found a single impact crater on this region,” said John Spencer, member of the Southwest Research Institute (SwRI) in Boulder, Colorado during a news briefing this Wednesday. If you look again at the closeup image of Pluto, you may ask yourself why you didn’t notice that right away. This is very significant, because the presence (or absence) of craters indicated a planet’s crust’s age.
PLUTO’S SURFACE AS OLD AS DINOSAURS
“Just eyeballing it, we think it has to be probably less than 100 million years old,” estimated spencer, deputy leader of New Horizons’ geology and geophysics investigation (CGI) team. This means that Pluto’s geology was probably active while the dinosaurs roamed the Earth. And that is very recent, on a cosmic scale. “It might be active right now. With no craters, you just can’t put a lower limit on how active it might be.”
To be clear, all of this new scientific knowledge was garnered from one photo of one percent of Pluto’s surface. Jeff Moore, of NASA’s Ames Research Center in Moffett Field, California, said of the surface: “[it’s] one of the youngest surfaces we’ve ever seen in the solar system.”
OTHER ACTIVE BODIES, OTHER EXPLANATIONS
A few other small planetary bodies in our solar system have shown ongoing geologic activity. Enceladus, a geyser-shooting moon of Saturn, and the hot and volcanic Jovian satellite Io. The difference is that these planets’ interiors are heated by the gravitational tugs of Saturn and Jupiter, respectively. This process is known as tidal heating.
“This can’t happen on Pluto, because there is no giant body that can deform it on a regular basis,” wondered Spencer. “This is telling us that you do not need tidal heating to power geologic activity on icy moons. That’s a really important discovery that we just made this morning,” he concluded in deadpan humor to applause of the audience.
The thing is that Pluto and Charon aren’t tugging on one another, though, because “Pluto and Charon are in tidal equilibrium,” objected Alan Stern. “Charon orbits equivalent of geosynchronous orbit, and it is also spinning at the same rate that pluto spins. So there is no significant change in tidal energy anymore.”
PRELIMINARY HYPOTHESES
One hypothesis as to how Pluto and Charon have managed to remain active is by having never lost their internal radioactive heat for a much longer amount of time than scientists had estimated possible. There is also the possibility that both Charon and Pluto once possessed subsurface Oceans, like Europa, which froze so gradually that heat was continually released into either body’s crusts.
Whatever it is we continue to learn of the Plutonian system as images and data of this brief flyby continue to return to Earth, one thing is for certain: the cost and risk involved in sending this piano-sized probe to flyby Pluto was worth the quantity and significance of scientific knowledge we are gaining, and we know this with one closeup image of Pluto.
