Thoughts about Pluto

Clyde Tombaugh discovered Pluto 80 years ago today. Coincidentally, I spent much of last week working on charts to help people locate and observe Pluto in 2010. And just two weeks ago, Kelly Beatty published an article describing new and exciting findings about Pluto. So this planet — or whatever you want to call it — has been on my mind a lot recently.

Hubble Pluto map longitude 180
Four years of processing by 20 computers have turned a set of Hubble Space Telescope images of Pluto, each only a few pixels wide, into this map of its complex surface.
NASA / ESA / Mark Buie
I've always been perplexed by the people who felt upset when Mike Brown and his team discovered another object both larger and farther from the Sun than Pluto. For people who don't remember, this object was first named 2003 UB313, then Xena (after the Warrior Princess), and finallly and most appropriately, Eris, after the goddess of discord.

Ever since the Kuiper Belt was discovered in the 1990s, it's been apparent that Pluto is a member of this family. And it seemed extremely likely even then that it was only a matter of time until some Kuiper Belt object proved to be bigger than Pluto. But this doesn't detract from Tombaugh's discovery at all — quite the contrary!

It was obvious from the moment its orbit was calculated that Pluto was different from the other big planets. It seemed like a dead end, a footnote. Now we know that on the contrary, Tombaugh's discovery was a beginning, not an ending; he was a half century ahead of his time when he found the first KBO.

As for me, Pluto's luster certainly hasn't been diminished, since it's the only Kuiper Belt object that I'll ever see through the eyepiece of my own telescope — unless I someday acquire a monster Dob that's capable of splitting Charon from Pluto or spotting 16.9-magnitude Makemake, as Steve Aggas has done.

It's been several years since I last looked at Pluto. I guess I'll have to take a look this summer, if only as a quality check on my own charts. Pluto is in a unique position now, poised to enter the Small Sagittarius Star Cloud, which is truly crawling with 14th-magnitude stars of comparable brightness. I have no idea whether that will make Pluto harder or easier to spot.

14 thoughts on “Thoughts about Pluto

  1. AGS

    FOR ANY ONE INTERESTED I WOULD RECOMMEND “BEYOND PLUTO”.
    A BOOK DEALING WITH THE BELT AND LONG VS SHORT PERIOD COMETS. THE BOOK DETAILS THE DIFFICULTY OF IMAGING THESE DISTANCE OBJECTS WHOSE RELATIVE MOTION IS VERY SLOW AND WHOSE ALBEDO IS VERY LOW. THE SOPHESTICATION AND EXPENSE OF THE EQUIPMENT REQUIRED REALLY MAKES IT DIFFICULT FOR AN AMATEUR TO CONTRIBUTE.

  2. Chuck McPartlin

    I suspect that you’ll find this Pluto anniversary to be the 80th, not the 70th, if you subtract 1930 from 2010.

  3. Tony Flanders

    Gack, you’re right — 80 years it is. The article has been amended accordingly. I must be arithmetic-challenged today.

  4. Laurel-KornfeldLaurel Kornfeld

    Pluto and Eris are both Kuiper Belt Objects and small planets. One does not preclude the other. For many people, it’s not the discovery of Eris that is upsetting; it’s the repeated pronouncements by Brown claiming he “killed” Pluto and denying that the debate about Pluto’s planet status continues.

    Please do not blindly accept the controversial demotion of Pluto, which was done by only four percent of the International Astronomical Union, most of whom are not planetary scientists. Their decision was immediately opposed in a formal petition by hundreds of professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA’s New Horizons mission to Pluto. Stern and like-minded scientists favor a broader planet definition that includes any non-self-luminous spheroidal body in orbit around a star. The spherical part is important because objects become spherical when they attain a state known as hydrostatic equilibrium, meaning they are large enough for their own gravity to pull them into a round shape.

  5. Anthony BarreiroAnthony Barreiro

    Pluto is what it is. Our names for it may change as our understanding evolves, but our nomenclature does not change the properties of what we are naming. The zen sage Osho admonishes us not to mistake a finger pointing at the moon for the moon itself. Perhaps we should also not mistake a highly processed composite Hubble Space Telescope image for a Kuiper Belt Object.

  6. Anthony BarreiroAnthony Barreiro

    Pluto is what it is. Our names for it may change as our understanding evolves, but our nomenclature does not change the properties of what we are naming. The zen sage Osho admonishes us not to mistake a finger pointing at the moon for the moon itself. Perhaps we should also not mistake a highly processed composite Hubble Space Telescope image for a Kuiper Belt Object.

  7. jiminboulder

    The problem isn’t with Pluto or the definition of a planet, it’s with astronomers who feel compelled to classify, systematize, and categorize everything in the universe, whether it needs it or not. Geographers are still getting along after all these centuries with NO definition of (get this) a continent. Why should someone’s hairsplitting definition of planethood matter in understanding the truth about what’s up there, outside the orbit of Neptune?

    Ease up, IAU. Discover the joys of non-classification.

  8. Michael C. Emmert

    It’s not a planet, it formed in the Sun/Neptune L4 or L5 point as a binary with Eris. Pluto gave Eris a gravitational slingshot boost to propel it way out there. I’ve modeled this on GravitySimulator. Triton and Haumea formed at the other Lagrange point, I’ve modeled that, too. If, at closest approach, the objects follow one behind the other, their rotation is cancelled and the objects collide. This explains Haumea’s moons and collisional family.

    Triton is larger than Pluto or Eris because it ate Neptune’s original moons, add the mass of Uranus’ moons to Pluto and see for yourself. Haumea’s ice was stripped off in the collision, it’s like the stripped core of Pluto. Jim, Laurel, classification is a joy :D

  9. Freedom Star Fighter

    For the past number of years some (often self-appointed little tin gods) have told the public that something is so BECAUSE THEY SAID SO. If an untruth is repeated often enough then it has the appearance of being a fact. Everything from political heads of whatever, entertainment (“this is your new American Idol”), the so-called childhood obesity epidemic (look at the “heroin chic” teen models), the “H1N1 pandemic”, “the economy’s booming” – NOT, and Pluto being a “dwarf planet”. They still use the word “planet” in this excuse of a classification and it leads to this: the “clear-the-orbit-of-debris” factor doesn’t wash because that “disqualifies” other planets as well – look at the Greeks and Trojans asteroid clusters “ahead” and “behind” the planet Jupiter in its orbital path. One question I had on an Artificial Intelligence class exam in college had a Zen flavor to it. My instructor told me to write down just what you see in the given diagram. Don’t speculate on what happens next or on anything, just describe what you see – that’s it. Look at the picture on this page. We know Pluto orbits the sun, and it’s spherical in shape. If it looks like a duck, swims like a duck, quacks like a duck then Pluto is a planet. It’s thaty.

  10. Jeff Gortatowsky

    Fortunately after reading most of the comments here, science still does not care about your emotional tantrums. Science IS what is. Whether it changes tomorrow, or a millennia from now, or never, science IS what is. And all the wishful thinking, ranting, and frothing of the mouth, or fore Pete’s sake conspiracy theories(!), won’t change that. Today and until proven otherwise, it is what it is. Walking like a duck, talking like a duck, is not science. DNA checks showing its a duck is science. ;)

  11. Tony Flanders

    I’m intrigued that this degenerated so quickly into the nomenclature debate — which I barely referred to. A few comments. I don’t really agree with Jeff Gortatowsky about ducks. We do not understand DNA to the level that it can distinguish what’s a duck and what’s not a duck. Science is all about making categories, and there’s inevitably a subjective component to that. As for continents — of course geographers don’t need a definition. That’s because there’s a fixed set of islands-or-continets to work with, and informal agreement about them is altogether satisfactory. Nobody cared about the definition of a planet either, before the Kuiper Belt was discovered. The whole reason there’s a crisis of definition is because the objects in question are constantly growing, not fixed, and constantly changing in light of our knowledge of exoplanets.

  12. Melissa

    WE HAVE 10, NOT 8. There’s MORE out there than we know. I know one should be open-minded, but I’m still saying PLUTO & ERIS ARE PLANETS. I wish I could travel to the ISS, but with my life and medical condition, that would be impossable.
    I don’t have any kids, but if I did, I’d change the answer on their paper. If the teacher had a problem with that, they could talk to me. As I said, WE HAVE 10, NOT 8.

  13. Ed Case

    Hay, I am 67 years old and been an amateur astronomer as far as I can remember. Before I was six years old my grandfather was showing me the constellations.

    Pluto was always the nineth planet and why should science change it. GDit, leave it like it was.

  14. Russell Fero

    "Please do not blindly accept the controversial demotion of Pluto, which was done by only four percent of the International Astronomical Union, most of whom are not planetary scientists."

    "Science IS what is. Whether it changes tomorrow, or a millennia from now, or never, science IS what is."

    "Their decision was immediately opposed in a formal petition by hundreds of professional astronomers led by Dr. Alan Stern"

    Bottom line: Only 4% of the AU decided for the remaining 96%. Worse – the 4% were mostly NOT planetary scientists. This little caper of theirs was like a back alley convention of dentists voting to decide what the brain surgeons would call the brain.

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