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The Rise And Fall Of The Once Ninth Planet -- Pluto

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The Humble Beginnings Of Pluto's Discoverer

Many of you who enjoy the study of astronomy have no doubt heard that it was Clyde Tombaugh who discovered Pluto, way back in 1930. It was a triumph of a dedicated astronomer who'd spent endless hours photographing regions of the sky and examining photographic plates, looking for Planet X.

With a humble beginning as a Kansas farm boy, Tombaugh became interested in astronomy. While I present some of the history here, you can get additional information from the Clyde Tombaugh biography at Wikipedia.

While growing up on his parent's farm, Clyde built his own telescopes, and used them to make detailed observations of the planets. He sent those drawings and details of his hand-made instruments to Lowell Observatory in Arizona. The staff at Lowell Observatory were impressed enough that they offered him a job.

Clyde did later go to college at the University of Kansas and received a Bachelors and Masters degree in astronomy, and according to the wikipedia article did this while he still employed at Lowell Observatory.

Some Personal Recollections

As it happens, I grew up in Kansas myself about 40 miles or so from the place Tombaugh grew up (some 40 years later albeit), I can give some information about Clyde Tombaugh you won't find in the wikipedia article.

In my neck of the Kansas woods (figuratively speaking, there were no woods in that part of Kansas), we school kids were told a lot about Clyde Tombaugh. While we were in grade school, we knew already that Clyde was world renowned for his discovery of Pluto. So he was a local hero. Since I was also interested in astronomy as a child, Clyde Tombaugh was doubly my hero.

Clyde Tombaugh grew up on a western Kansas farm, hardly the typical background for a would be future astronomer. If you're not familiar with Kansas, it's flat. Really flat. No hills, like what observatories are usually built upon. I remember using one of my own early telescopes to gaze at the top of a grain elevator that was nearly 15 miles away. That's how flat parts of Kansas are. There were certainly no big observatories in our part of the state from which to draw inspiration, though a relatively close college did have a telescope used as part of its general physics training.

I first personally encountered Clyde Tombaugh during my quest to find a college to attend for graduate training. At that time he was a professor of Astronomy at New Mexico State University. Later in my life I had a couple of other opportunities to chat a bit with Clyde.

I found that he still had in his backyard one of his early telescopes. It was a long focus Newtonian telescope, a 9 inch I believe. I think he said he'd used parts from a milk separator to make a mount. Even the sight of that telescope impressed me. I certainly don't have any of my early equipment. It seemed to me almost as if Clyde had a profound sense of history, and knew to keep that telescope.

In our few chats, Clyde once mentioned a trip he'd taken to Italy where he got to see some of the sites related to Galileo's history. He mentioned that Galileo was a hero of his -- an inspiration. I told him about how I and my grade school classmates were told about him and his discovery. I told him that having grown up not far from his childhood home, I'd always thought of him as a hero and inspiration. I think it pleased him to hear about how we as kids were taught so much about him.

I asked him how he'd come to be involved in astronomy. He told me of a time when as a child, he was out in the barn doing some chores. A thunderstorm was building up, and then a violent hail storm ensued. He had to sit it out in the barn, and could hear the hail stones pounding on the roof. When it was over, he stepped out to see that the crops had been destroyed. He said he decided that there had to be a better way to make a living than that.

The Discovery Of Pluto

The finding of Pluto wasn't an incidental discovery. One of the major players in the effort was W. H. Pickering, who was one of the hunters of the mysteriously missing Planet X. At that time, a number of astronomers including Pickering felt that there were perturbations of Uranus and Neptune in their orbits that could best be explained by there being another, undiscovered planet beyond the orbit of Neptune. It was this mysterious planet that Clyde Tombaugh was laboring to discover. So Pluto was found during this methodical search for a planet.

And discover it Clyde did, using a blink comparator. What a blink comparator did was to let an observer alternately see either of two photographic plates in quick succession. If something was in a different relative position on the two plates, it would appear to be jumping back and forth. It was a quick way to identify moving objects like asteroids, comets, or -- Planet X. After considering many suggestions, the Lowell observatory staff settled on Pluto for the name of the new planet.

The only problem was that as astronomers extensively examined the newly discovered planet, it became obvious to them that while in an orbit beyond Neptune, Pluto was way too small to be causing any significant perturbations to Neptune or Uranus. So it was a planet, but clearly not the sought after Planet X. Since then, more precise knowledge of the masses of the the outer planets has explained the perceived perturbations, eliminating the need for a Planet X hypothesis.

The Fall Of Pluto

For decades, all was well in the solar system family, with Pluto being accepted as the ninth planet. It was known from the beginning that it was only about the size of our moon, but was round, bigger than an asteroid, and circled the Sun. Nothing else was asked of it as a Planet.

Then came discoveries of similar sized bodies beyond Pluto, out in the Kuiper Belt. I'm not sure what about that seemed to disturb the astronomical waters, maybe the idea that the number of planets was getting out of hand. Or maybe the fact that some moons around Jupiter, Saturn, and Neptune were as big or bigger than Pluto.

Whatever caused the unrest, the astronomical field split into two camps. One camp thought that the criteria for being a planet should be simple -- big enough to be spherical, and orbit the Sun. That camp wanted to keep Pluto classified as a planet.

Others wanted to add a new category of planets, called Dwarf Planets. This new category of objects would contain those bodies that orbit the Sun, are big enough to be spherical, but not big enough to clear their respective neighboring regions of planetesimals. This camp wanted to classify Pluto as a Dwarf Planet.

I'm in the first camp, both because I'd grown up with the concept of Pluto as the ninth planet, and because I didn't want to see Clyde Tombaugh's discovery be altered from that of having discovered the ninth planet. But alas, for the time being, the Dwarf Planet camp has won the day. Pluto is now considered to be a Dwarf Planet, and has been dethroned as the solar system's ninth planet.

My Satirical Comment On The Fall Of Pluto

To pay homage to poor Pluto, I wrote a little limerick I call Pluto's Lament. It goes as follows:

A Planet Called Pluto By Name
Grew Vast In Stature And Fame.
It Had Its Own Moon,
And Yet All Too Soon
Was Demoted To Dwarf Planet Shame.

Pluto's Lament Small Poster Poster

You can purchase the limerick on a large selection of t-shirts, dark t-shirts, and sweatshirts. You can also get it on some drink ware products, including coffee mugs.