People ask me all the time, “Bil, why are there only eight planets in our solar system?” You see, not too long ago there were nine planets. In fact, all the way up until 2006 there were nine planets in our solar system. There was Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. But in 2006 a whole bunch of scientist got together and decided that Pluto was too small to be a planet.
Pluto was discovered by Clyde Tombaugh on February 18, 1930, and for seventy-six years, from 1930-2006, Pluto was a perfectly well behaved planet way out there on the edge of our solar system, revolving around some 3,670,050,000 miles away from our sun. I don’t know how Pluto suddenly became too small to be a planet, but it did. (Read Mike Brown’s wonderful How I Killed Pluto and Why It Had it Coming for more, what they call, “actual information,” on the subject. I hadn’t read it when I wrote this.) Maybe Pluto didn’t finish his supper, or drink his milk, or eat his vegetables. That’s why I always tell my kids stuff like: “Make sure you eat all your supper. Remember, there are starving planets out there on the edge of the solar system.” And, “If you don’t eat your peas you’ll never be a planet.”
Now-a-days there’s only eight planets in our solar system. The planets are Mercury, Mars, Earth, Venus, Jupiter, Saturn, Uranus, and Neptune. But when I was a kid, there were eleven planets. No, really. When I was a kid there were eleven planets in our solar system. No kidding. There was Mercury, Mars, Earth, Venus, Jupiter, Saturn, Uranus, Neptune, Pluto, and then Margaret, and Gertrude.
Margaret and Gertrude were well over four billion miles away from our Sun so scientists didn’t know much about them. All scientists could tell through their telescopes was that Margaret was a solid planet, like Earth, and Gertrude was a gas planet, like Jupiter- only smaller. The only thing was, Gertrude wasn’t round like other planets. As far as the astronomers could tell Gertrude was shaped like a funny looking poodle dog. Don’t laugh. It’s a known fact. Planet Gertrude looked like a big pink poodle. As a matter of fact, they called it, “Gertrude the Poodle Planet.” It’s true. Ask your science teacher. Some important scientists of that era believed that that was where all poodles had come from. Gertrude the Poodle Planet intrigued the astronomers here on Earth, and so the astronomers built a space ship and sent it out into space to study Gertrude.
As the space ship approached, it became obvious to the astronomers that Gertrude was not a big, pink poodle. Nope, she just looked like one. Truth be told, Gertrude the Poodle Planet was really a huge balloon- just like you get at parties- that had been twisted and shaped by some cosmic clown to look like a big pink poodle! And there she was, planet Gertrude, stuck to the wall of the solar system by static electricity. You know, like when you take a balloon and rub it on your hair for awhile, and then stick it to the wall and it stays there?
Static electricity, by the way, occurs when you get more electrons- the negatively charged particles in atoms- built up on an object, then protons- the positively charged particles. Those negatively charged electrons want to get off of the atom so they look for a positively charged place to jump. When you walk across a carpet in your socks, for example, and then touch a doorknob you sometimes get a little shock. This shock comes from the extra electrons you built up walking across the carpet jumping to the door knob when your finger gets near it. Same thing with a balloon. When you rub a balloon against your hair negative particles, or electrons, build up on the surface of the balloon. If you then hold that balloon against the wall the atoms in the wall react to the presence of the negative electrons. The atoms in the wall react by shifting their protons, positively charge particles, toward the negatively charged particles on the surface of the balloon. And bam! The negative and positive particles hold onto each other like magnets. And the balloon sticks to the wall. That’s static electricity.
Or, another example is when you take off your hat in the winter and all your hair stands up. That’s cause opposite particles- negative and positive- stick to each other like magnets but particles with same charges like to get as far away from each other as possible. When you take your hat off it sweeps a whole bunch of electrons with it, leaving your individual hairs covered with protons. Protons don’t like to be next to other protons so all your hairs stand up as the protons try to get away from each other. If they weren’t connected to your head, all your hairs would jump right off your head. See?
Anyway, Gertrude, the big, pink balloon planet had been stuck to the wall of the solar system by some extraterrestrial being. When the space ship that the astronomers sent to explore Gertrude tried to land on Gertrude’s surface a sharp little point on the bottom of the spaceship poked Gertrude like a needle, and POW!! Gertrude the balloon planet popped! The astronauts we’re never seen again.
As it turns out, Gertrude the Poodle Planet belonged to the planet Margaret. When Gertrude popped two things happened. First, planet Margaret started to cry. Tears fell off like she was emptying her oceans. Second, the force of Gertrude the Poodle planet popping blew planet Margaret right out of her orbit into the rings of Saturn. I don’t know if you know this, but the rings of Saturn are razor sharp. When planet Margaret hit Saturn’s rings Margaret got diced up into a million little pieces. And that’s what happened to Gertrude and Margaret, the tenth and eleventh planet in our solar system.
But- that’s not the end of the story. You see, Pluto, as I’m sure you’ve heard, is supposed to be a big ball of ice. Whether or not Pluto is a planet might be debatable, but everyone agrees it is a big ball of ice. Despite any real scientific evidence to prove my theory, I believe that Pluto wasn’t always a ball of ice. I think Pluto used to be a tropical paradise planet, just like Hawaii is a tropical paradise. (Not that I’m suggestion Hawaii is a planet. That’s absurd.) “But,” you say, “Pluto can’t be a tropical planet because it is so far away from the Sun!” Well, just think about this: Hawaii is far away from the rest of the United States and yet Hawaii is still a tropical state. It’s pure logic. Distance from one place to another doesn’t determine tropicalness. So, if Hawaii can be far from the continental US and still be tropical then Pluto can be far from the Sun and still be tropical. Right?
“Hold on a second!” I hear you shout. “Hawaii is warm because it is near the Equator. And places near the equator are warmer than places farther away from the Equator!”
Well, I thought about that, too. But, consider this: Pluto is really small. In fact, Pluto is so small that it isn’t even considered a planet anymore. So, because it is such a small place we can assume that the entire planet is close to its equator. And, as we all agree, things close the Equator are warm. As matter of fact, Hawaii is almost 1000 miles from Earth’s equator. But Pluto is only about 1485 miles in polar circumference– that means it is only 1485 miles around, measuring from top to bottom to top- all the way around.
I emailed NASA just to make sure that that was the right size for Pluto and here’s what they told me. I have to say this slow ’cause I don’t really understand it completely, but if you learn it now, you can grow up to be a NASA scientist and maybe you can reinstate Pluto’s planetary status.
This is what my friend Randii, at NASA, told me about how we know how big Pluto is. He said, “We’re not absolutely positive about Pluto’s polar or equatorial circumference. The size we’ve determined is based on a process called ‘occultation.’ Occultation is the temporary hiding, or disappearance, of a celestial object as another object moves in front of it. (That means, they can tell how big something is by how much of another thing it covers. For example, if you knew how big a quarter was but not how big a penny was you could put a penny on top of a quarter, figure out how much of the quarter the penny covers, and then you could figure out about how big the penny is. Get it? That’s occultation in a nut shell. Go on, try it out. Your parents will put in an application to Harvard tomorrow if you start doing occultation at supper.) Anyway, scientists figured out how much Pluto was blocking out the light from a star behind it as Pluto moved in front of that star. The radius we have for Pluto is based on that occultation. As such, we don’t have an exact equatorial or polar radius for Pluto. We just have an estimate of Pluto’s general radius. These occultation measurements are the current best approach for determining the planet’s radius.
Unfortunately, opportunities for occultation don’t occur often and since we don’t know how much of an atmosphere Pluto has, the number we have is a bit flaky. So, we just use 1195 km for the radius of Pluto. That converts to 742.5 miles. If we know the radius we just have to run it through the simple formula 2 x Pi x R, or, in Pluto’s case, 2 x 3.1414 x 742.5= 4665 miles.” NASA people always talk like that. They think everybody knows what occultation and ‘Pi times radius’ means, which, of course, you do.
That whole Pi business just means that Pluto’s North and South poles are only about 743 miles from Pluto’s equator. So, Pluto’s poles are closer to Pluto’s equator than Hawaii is to Earth’s equator. We’ve already agreed that things close to the Equator are warm, so I reckon that at one time Pluto was probably warm all over. You follow? In fact, I think Pluto was such a warm, tropical paradise that the other planets used to vacation on Pluto.
When Gertrude, the Puddle planet, exploded Margaret started to cry, and then she was diced to pieces on Saturn’s rings. All those tears coming off of Margaret flooded Pluto and blocked out what little sunlight gets to Pluto. The blockage of the sunlight, combined with the flooding of Pluto, caused the whole planet to freeze over into the big snowball that is today.
When Pluto froze, all the other planets in our solar system quit visiting Pluto for vacation. When that happened Pluto’s tourism based economy plummeted and thus Pluto could no longer afford to buy enough planet food. That’s when Pluto began to shrink. When it shrank too much, scientist took away its planetary status.
And, that, my friends, is why there are only eight planets in our solar system today.
And remember, if you want to be a planet, stay close to you Equator, eat your supper, do your exercises, and don’t live near anybody who has a giant, poodle shaped balloon stuck to their wall by static electricity.
And if you want to work for NASA, just remember that Pi times radius equals circumference, and that occultation is the temporary hiding, or disappearance, of a celestial object as another object moves in front of it. Oh- and if you really want to work for NASA, you probably shouldn’t mention Gertrude the Poodle planet.