Yes, it is time for another caps-heavy post, right after the last one. But that’s only because SO MANY AMAZING THINGS ARE HAPPENING RIGHT NOW.

Over the years, astronomers have taken several images of Pluto. We haven’t ever seen it in detail before, though: until yesterday, Pluto was just a smudge at the end of the telescope. UNTIL YESTERDAY.

This animation shows the evolution of humanity’s view of Pluto, a cold world close to the edge of our solar system. That first image (the one that looks like 6 bright pixels) was taken after its discovery by Clyde Tombaugh in 1930. The last image of the whole planet was just beamed down to Earth by the New Horizons spacecraft yesterday:

The last image in the montage was just received this morning, just released at 2:00 CST today:

And along with that image was an image of Charon, Pluto’s large moon:

Before I write about any features of these images, I think it’s important to just stare at them for a while. These are new worlds. Worlds we knew pretty nearly nothing about TWO DAYS AGO. Pluto has been a mystery for decades and suddenly we can SEE it. We can see SPECIFIC FEATURES. In DETAIL. It is a REAL PLACE. If there’s anything more amazing than that, I haven’t experienced it.

Now for a few comments on the features we see in these images. Below are some exaggerated-color versions of the images of Pluto and Charon that we had as of yesterday. The different colors represent differences in composition.

As we can see, Pluto and Charon are not just dead, homogeneous rocks floating around in space; they are incredibly diverse, and much of that diversity won’t be studied for quite a long time – New Horizons will be sending back data from yesterday’s flyby for 16 months before we have all of it, and then it’ll take even longer to analyze it. The two most prominent features in these images, though, are the “heart” on Pluto, now unofficially called Tombaugh Regio in honor of Pluto’s discoverer, and the dark spot on Ceres, now unofficially called Mordor. We don’t know what either of those things are yet because we have a tiny fraction of the data, so I’ll (reluctantly) refrain from rampant speculation. When spectroscopy data and stereo images arrive, they’ll tell us more about what substances are there and the topography, respectively.

While the answer to most questions about Pluto is still “Nobody knows yet!” there are, of course, some important discoveries which have already been made. For one, as we can see in the close-up image of Pluto, it has huge mountain ranges, about 11,000 feet tall. Those mountains are made of water ice, coated with a thin layer of methane and nitrogen ice! If there is a veneer of nitrogen, that might indicate cryovolcanism on Pluto – we haven’t seen any active volcanoes on Pluto, but it is a possibility!

The other huge discovery from that image is the conspicuous lack of impact craters: Pluto’s been around for a long time, so one would expect that it’s been hit by a lot of rocks in space. All of the other icy worlds we’ve looked at have been orbiting larger bodies (Jupiter, Uranus, etc.), so those worlds are constantly recycling their surfaces as the gravity of their planets tidally stretches them. Pluto and Charon doesn’t have any tidal forces, though (they’re both too small, without enough gravity to stretch one another). So, the fact that Pluto and Charon don’t have many impact craters and do have geological features which look new tells us that tidal heating may not be necessary to recycle the surface of an icy world. This sounds a bit dry, but it overturns an assumption of geophysics that’s been in place for years! The fact that these small worlds can be geologically active even at an advanced age (Pluto’s no spring chicken) will, in the words of Dr. Alan Stern, New Horizons’ principle investigator “send the geophysicists back to the drawing board.” Basically, it’s a big deal.

This whole mission is a big deal. In fact, it’s a Big Deal. Pluto doesn’t look like any other world we’ve observed. It is astonishingly complex, unlike anything we’ve seen before. John Spencer, a lead scientist on New Horizons, said “It’s baffling in a very interesting and wonderful way,” and I think that sums it up well. The things we’ve already seen are absolutely awe-inspiring. IMAGINE WHAT WE WILL SEE NEXT.





Links to other resources:

NASA’s Press Release:

New Horizons Image Gallery (where the images in this post came from):

New Horizons In-Depth Payload/Instrument Information:

Nadia Drake’s Blog Post:

Phil Plait’s Blog Post:

(Note: you may have noticed I’ve been referring to Pluto as a “world” rather than a planet or a dwarf planet. That’s because I think quibbling over terminology isn’t particularly useful and being excited about new science is far better in every way. For what it’s worth, because Pluto hasn’t cleared its orbital path and the definition of “planet” has to apply to everything equally, either Pluto and 200 other things in our solar system are all planets or we’re left with our 8.)


2 thoughts on “PLUTO

  1. Pingback: PLUTO | Down Here on Earth – Dan Green Books

  2. Pingback: Pluto Update! | Down Here on Earth

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