Pluto at 82: A 'Chihuahua' Among Planets?

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On Feb. 18, 1930, American astronomer Clyde Tombaugh discovered the ninth planet, Pluto. As we celebrate the 82nd anniversary of its discovery, we are also reminded about the controversy that still surrounds this little world’s planetary status.

In light of the discovery of Eris in 2005, the following year the International Astronomical Union (IAU) voted to define what a “planet” actually is. Unfortunately for Pluto, it became a rounding error and joined Eris in the “dwarf planet” club.

WATCH VIDEO: PLUTO … DEMOTED!

Though many saw this as a demotion, in actuality it was an indication about how exciting and rich our solar system is. Discoveries of minor objects in the Kuiper Belt (a region of space outside the orbit of Neptune) and beyond are increasing, and as our technology improves, more discoveries are inevitable.

ANALYSIS: Spacecraft Sprints to Within a Billion Miles of Pluto

As Eris discoverer Mike Brown, planetary scientist at Caltech, discussed during an interview on Friday, camera and telescope sophistication is increasing and we are only just seeing the tip of the minor body iceberg in the outermost reaches of the solar system.

“If you can take one of these big cameras and put it on a big telescope, you’re in business. And this is actually happening,” Brown told Universe Today’s Fraser Cain on Friday’s G+ Hangout interview.

“I think the next big thing in finding huge numbers of Kuiper Belt objects and distant, faint ones is this project that’s underway in Chile right now: the LSST (Large Synoptic Survey Telescope).”

Brown believes that such a powerful system, comprising of a 6-meter telescope plus a “huge” camera will unveil the population of small Kuiper Belt objects and give us an idea about how many mini-worlds orbit at even more extreme distances.

ANALYSIS: Pluto May Live in a Rough Neighborhood

But we are also looking forward to the rapid approach of NASA’s New Horizons mission to the Kuiper Belt that will zoom past Pluto in 2015.

“It’s as if we had traveled the world and only found large dogs like the Labrador and never found the Chihuahuas.”

– NASA New Horizons P.I. Alan Stern

New Horizons principal investigator Alan Stern joined us on the weekly G+ Space Hangout on Thursday to give an update on the mission and discuss his outspoken opinion about Pluto’s true planetary status.

“I think that when people see Pluto (during the New Horizons flyby), they’re going to figure out what a lot of planetary scientists have already figured out,” Stern said. “Is that the outer solar system is teeming with small planets … (Pluto) is admittedly a new “species” of planet if you will.”

“It’s as if we had traveled the world and only found large dogs like the Labrador and never found the Chihuahuas. Well, would we say they’re not dogs just because there’s too many of them and we can’t keep track of their names and they are smaller?”

Stern is highly critical of the IAU’s decision to restrict the solar system to just eight planets — Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune — and many minor worlds that don’t “fit” with the new planetary definitions.

“When you list the characteristics of the dwarf planets, they have solid surfaces, atmospheres, seasons and polar caps, cores and often satellite systems; all the same attributes as the larger planets, except they’re just a smaller version.”

ANALYSIS: Hunting Pluto’s Dangerous Rings

Brown, who lightheartedly calls himself “Pluto Killer” on Twitter (as his discovery of Eris ultimately led to the IAU vote on what a planet actually is), also discussed the huge amount of variation in Kuiper Belt objects and commented on how Eris and Pluto size up:

“One thing we know very well is that Eris is 26 percent more massive than Pluto, which is actually quite a big amount. The total extra mass that Eris has compared to Pluto is more than the mass of the entire Asteroid Belt — this is not an insignificant amount of extra mass … the fact that (Pluto and Eris) are the same size makes people say they are ‘like twins,’ but the fact that they are the same size, I think, makes them nothing alike at all. Eris is mostly rock with a thin layer of ice on the outside; Pluto is much more ice on the outside and rock on the inside. “It’s really quite a strange thing. If you’d have asked me even just two or three years ago what all of these big objects were going to be like, I would have said: we know about Pluto, we know that Pluto’s about two-thirds rock and one-third ice and we would guess that everything else out there in the outer solar system is the same way. And what we are finding is an incredible amount of variation. There are these things like Eris and also the very strange Haumea, which is mostly rock, and Quaoar, mostly rock; there are these other things that are mostly ice.”

Regardless of the status of Pluto’s planethood, as we increase the sophistication of ground based observatories and look forward to New Horizon’s outer solar system encounter in 2015, our understanding of this mysterious region is about to become its clearest in the 82 years since Tombaugh’s historic discovery.

When we see the world through the eyes of New Horizons, we’ll see what looks like a planet. And yet due to a reclassification of the solar system (and our place in it), that “planet” is in fact a dwarf planet. But as Stern points out, seeing is believing and public opinion may be the deciding factor in the “Great Pluto Debate,” regardless of how the IAU classifies celestial bodies.

Watch The Weekly Space Hangout with Alan Stern (Feb. 16):

Watch the Mike Brown Interview with Fraser Cain and Nancy Atkinson (Feb. 17):

Source: Wired (Geek Dad)

Image credit: NASA