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We Heart Pluto

October 27th, 2015

Pluto (and its heart shaped landscape). Image courtesy NASA

We can’t see it without a telescope, it was discovered back in 1930 by a young farm boy from Kansas named Clyde Tombaugh, and it gets so little respect that it was officially labelled a “dwarf planet” by the International Astronomical Union in 2006.  Why should we care about it?  What’s there to learn from it?

Clyde Tombaugh discovered Pluto in 1930. Photo credit: Wikimedia Commons/public domain

Astronomers learn about things by pointing telescopes at them. However, there is only so much we can learn from a distance.  So, sometimes, we take a long trip to go there and see close up.

NASA’s New Horizons Mission did just that to Pluto.  The spacecraft was launched in 2006, and spent nine years getting all the way to Pluto … and finally got there this past July. It snapped a whole bunch of pictures and collected all sorts of data and then kept on going, never stopping! We are still receiving and analyzing the data and images.

Is there anyone on it?  Nope, New Horizons is a robot with telescopes and detectors galore.

But nine years? What took so long?  As of Halloween, 2015, the distance to Pluto is about 34 times that of the Earth to the Sun: more than 3 billion miles.  If you go 3 billion miles in nine years, then, on average, you’re going about 10 or so miles per second!  That’s actually pretty fast!

It’s so cold there, what could they possibly find?  It is cold and icy out there, and astronomers have long known that the temperature on Pluto 380 degrees below zero (Fahrenheit). The coldest place on Earth gets down to 126 below zero, and not many things work well in that kind of cold that we could use or build.

So, why bother?  The New Horizons team did what all explorers have always ever done.  They go there because no one ever has, and because there is new knowledge to be won.  But mostly, it’s all about curiosity.  Little babies are curious about the world around them, so New Horizons is like humanity’s little baby, seeing, touching and scooting around to explore.

The pictures and data that have been sent back by radio transmissions from the spacecraft are truly astounding. 

What we’ve seen is that the surface of Pluto is covered in nitrogen and methane ice .  This is really cold ice!  Pluto does have a lot of water ice, too, but it’s so hard from being so cold that the water ice is as hard as rock.  All the mountains you see are made from water ice.  Elsa from “Frozen” would really like it there. And it moves! The ice evaporates and makes an atmosphere for Pluto.

Pluto. Image courtesy NASA

The color of Pluto is also strange.  It’s a mucky orange.  That muckiness comes from the the methane and carbon monoxide in the atmosphere that gets broken apart by the Sun’s ultraviolet light and recombines into simple and odd heavy molecules called tholins .  Tholins are like the smog around a big city, like New York or Los Angeles.  So, it gently rains a frosty smog on Pluto, covering it with a sheen of orange.  Crunchy, new-fallen smog!

Pluto: Image credit NASA/JHUAPL/SwRI

Just as exciting is Pluto’s biggest moon,  Charon . It’s almost as big as Pluto itself! It’s got a huge canyon that seems to go around the entire moon — about 600 or so miles across. The north cap of Charon is coated with the orange smog of its parent (dwarf) planet.  This dark patch has been named “Mordor” after the land of the evil wizard in “Lord of the Rings.”

Actually, all the places on Pluto and Charon are named for villains and bad guys from fictional stories.  That’s because Pluto is Greek mythology’s god of the underworld, and Charon was the ferryman who would take the dead across the river Styx to Hades.

So, we’ve found that Pluto and Charon are active worlds with atmospheres, glaciers, soaring mountains of ice and smoggy frost.  We would never have gotten that from a point of light in the sky.  We only got that by visiting.

New Horizons is now continuing out into the space between the stars.  But, some of Clyde Tombaugh’s ashes, who passed away in 1997, are in a tiny can on the spacecraft.  So, Clyde is sort of an interstellar traveller! And it all started with his observation of a tiny speck in the sky.


Thanks, Jason, for the article! Jason Kendall is the Astronomy liaison at William Paterson University in New Jersey.  And HTE is always thrilled when he explains what’s going on in space!

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