Our Zettameter Galaxy

As you can probably tell, I’ve been on a memorization kick lately. It isn’t just geography. I’ve also been learning the unit prefixes: word stems like centi- and kilo- that tell you how much of something you have. A millisecond is a thousandth of a second, a gigabyte is a billion bytes, and so on.

But those are the common ones, the ones you hear about in everyday life. Me, I get a geeky kind of thrill from checking out the more exotic prefixes at the remote ends of the scale, the ones with bizarre names you never hear except in articles about really far-out science experiments.

Let’s take a look.

Tera- means trillion, 10 to the 12th, which you do hear occasionally when you’re talking about hard drives: the bigger ones on the market now are up in the terabyte range. You don’t hear much about terameters, though, because if you wanted to talk about a trillion meters, you’d probably just say a billion kilometers. A terameter is about Saturn’s distance from the sun.

Next up is peta-, a quadrillion, 10 to the 15th. A petameter is one-tenth of a light year, and doesn’t even get us close to the nearest star. A few petameters is a rough estimate for the radius of the Oort Cloud, which is where comets live when they’re not busy getting all up in our space.

An exameter is a quintillion meters, 10 to the 18th, or about a hundred light years. The Pleiades (or “Seven Sisters”) star cluster is about 4 exameters from Earth.

To span the diameter of our galaxy, though, you have to go all the way up to one zettameter, a sextillion meters, 10 to the 21st.

The very last prefix is yotta-, a septillion, 10 to the 24th. And because 260 yottameters is the diameter of the observable universe, it really is the last distance unit you’ll ever need.

So that’s my burst of geekiness for the day. Maybe not interesting to anybody besides me, but there we are.

What kind of weird stuff do you geek out on?


4 responses to “Our Zettameter Galaxy

  1. Dude you didn’t do the cool small distances! And you totally left out beard-second. nanometers and such! comes on! lol Astronomers got their light year, why can’t us solid state guys have a cool unit like beard-second.

  2. Interesting post!
    I geek out about random topics, although lately my writing has cut away my time for looking for them. Oh well, eventually another few will fall into my lap from the sky anyway. . .

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