Sympathizing with the plight of Pluto: How solid is the definition of a planet?

Finally, Election Day is over! I’m not going to talk about politics because I need a month to get over the mud that was flung throughout the year. Plus, I’m still angry about the Electoral College and its existence.

So instead, I am going to try to answer a question that has stumped our society for the past few years: Is Pluto a planet or not?

First, the definition of a planet from ancient Greece: If it’s bright and moving across the nighttime sky, it’s a planet.

This was a horrible definition.

It excludes Earth (we can’t see it moving across the sky), and groups together objects that aren’t planets, such as the sun and the moon, with objects that are planets.

This definition didn’t change until thousands of years later when the Dutch created the first telescope. Suddenly astronomy was much more interesting.

Thus, the solar system was rearranged. The Earth was no longer the center of the universe, and the sun took its rightful place in, well, the center our solar system.

Then the ancient Greek definition of planets changed so that the sun and the moon were no longer grouped with actual planets. At that point, it’s also important to note that only five planets had been discovered, besides our own. There was Jupiter, Saturn, Mercury, Venus and Mars. The definition now changed to “if it revolves around the sun, then it’s a planet.”

Time went on and telescopes got much better, thus each new century brought a new discovery about our solar system. Uranus was discovered in 1781, Neptune in 1846 and Pluto in 1930.

At this point, we had the solar system most of us grew up learning, with nine planets revolving around one star.

Then why isn’t Pluto a planet?

Look at any generic picture of the solar system in your textbook, with eight or nine planets. If you look closely, each planet looks like they are spaced equally apart and maybe even about the same size. If you remember anything from our science classes of yesteryear, you’ll remember that planets are, in fact, spaced apart by massive distances and hardly any planets are equal in size — besides Venus and Earth being sister planets, anyway.

For example, Jupiter is massive compared to Earth. If we took a diagram of the planets and adjusted it so each planet was the correct size, the first four planets would be dwarfed by Jupiter and Saturn. Pluto, on the very end, would almost be non-existent.

Even if we did show the correct sizes, we would need to show the distances, as well. If Jupiter were the same distance away from Mars and Saturn as it is away from Earth yet still massive, then we would just see an overwhelming amount of Jupiter in our nighttime sky. Have you looked outside lately at night? Do you see a massive planet taking up most of your view?

Of course not. We know that Jupiter is 380 million miles away from the Earth.

All right, back to Pluto. Pluto, in relation to size, is tiny. How tiny? There are moons bigger than that object. Plus, it’s extremely far away from the sun.

This is when the Pluto Club comes in to say, “Leave Pluto alone!” Before you say anything, I want to say one word: Ceres. Heard of it? Probably not.

In 1801, astronomers discovered a new planet in the huge distance between Mars and Jupiter. Although small, it was declared a planet and named Ceres. That following year, astronomers discovered another similar planet in that same stretch of space, naming that planet Pallas. A few years later, Juno was discovered, and then Vesta.

Thought learning nine planets was hard? Try learning eleven. As astronomers discovered more similar objects, they began to become more uncomfortable calling them “planets.” Instead, a new category was created, the Asteroid Belt, and the “planets” were renamed.

Back to Pluto. A few years after its discovery, astronomers discovered other objects similar to Pluto in the same area. Once again, they were growing uncomfortable calling them “planets.” But they figured that they could ignore the other similar, icy objects around Pluto as long as no other larger icy object was found.

And that’s when Eris comes in to burst Pluto’s bubble. Astronomers had to rename that stretch of distant, icy objects (which included Pluto), and the Kuiper Belt was born.

Now Pluto, instead of being an uncategorized planet, has found its home with other icy objects.

The round-about answer to all of this is no, Pluto isn’t a planet. But planets still have a horrible definition. With the knowledge we are gaining, I think the word planet will either be redefined or it may even fall out of practice. Until then, we’ll have to say goodbye to Pluto the planet.

As we say in my hometown, don’t forget to be awesome.

This entry was posted on Monday, November 12th, 2012 and is filed under Opinion. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site.

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