Sciency Words: Eccentricity

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Today’s post is part of a special series here on Planet Pailly called Sciency Words.  Every Friday, we take a look at a new and interesting scientific term to help us all expand our scientific vocabularies together.  Today’s word is:


According to the dictionary, eccentricity means deviating from the established norms, especially in an odd or whimsical manner.  I’m sure we’ve all met eccentric people at some point in our lives.  In high school, I was involved in musical theatre, so I got to see eccentricity up close and personal.  But did you know actors and actresses aren’t the only ones who behave eccentrically?  The term can also be applied to the behavior of planets.

The established norm for a planet’s behavior is to orbit a star.  To be more specific, planets are supposed to circle stars, as in their orbits should be perfect circles.  The less circular a planet’s orbit is, the more eccentric it is said to be.  In fact, a planet’s eccentricity can be quantified by measuring just how un-circular its orbit is.

One of my planets in Super Planet Crash has an eccentric orbit.  Can you guess which one?
One of my planets in Super Planet Crash has a highly eccentric orbit. Can you guess which one?

The thing is, according to Kepler’s laws, no planet has a perfectly circular orbit.  The “established norm” is a myth.  They all travel along slightly ovular paths, sometimes coming a little closer to the Sun, sometimes moving a little farther away.  So it turns out that, just like people, all planets are at least a little eccentric.

P.S.: Today’s post is related to a series here on Planet Pailly about sciency video games.  To find out more, click here.  To start playing Super Planet Crash, a game where you can see eccentric planets in action, click here.

Sciency Games: Super Planet Crash

Today’s post is part of a series of posts profiling sciency video games. These are educational games, most available for free online, that can really help you gain a deeper understanding of science. Click here to find out more about this series.

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The Solar System is fragile. The orbits of all the planets are affected not only by the gravity of the Sun but by the gravity of their fellow planets. Not only that: the combined gravitational pull of all the planets affects the Sun, causing it to wobble in place. Our Solar System is like a big, complicated machine with lots of moving parts, vibrating and shuddering, ready to burst into a million pieces at the slightest disturbance.

Screen Shot 2014-04-26 at 12.38.20 AM
Lots of planets packed into a relatively small space.  This won’t end well.

So with that in mind, it’s time you tried to make your own solar system. In the game Super Planet Crash, you drop planets into orbit around a star. The larger the planet, the more points you’ll score, assuming you can keep all those celestial spheres from colliding or hurling each other into deep space. If you manage to keep your solar system stable for 500 rotations, you win the game (FYI: I have yet to win the game).

One of my planets in Super Planet Crash has an eccentric orbit.  Can you guess which one?
If you’re not careful, you might create some dangerously weird orbits, like the orbit of that little pink planet pictured above.

It’s one thing to know intellectually that the Solar System exists in this delicate balance; it’s another to see how easily that balance can be disrupted. That is ultimately the lesson this game is trying to teach. In fact, astronomers have discovered rogue planets out there, drifting through space without a star to orbit. Presumably this happens because of people like me trying to play Super Planet Crash.

Click here to start playing Super Planet Crash.

P.S.: Based on my current high score in Super Planet Crash, we can all be thankful I did not design the real Solar System.