Cosmos

"INFINITE: Bigger than the biggest thing ever and then some. Much bigger than that, in fact, really amazingly immense, a totally stunning size, real 'wow, that's big' time. Infinity is so big that by comparison, bigness itself looks really titchy. Gigantic multiplied by colossal multiplied by staggeringly huge is the sort of concept we're trying to get across here." - Douglas Adams, The Restaurant at the End of the Universe

This is the sort of scale, put to words beautifully by the genius of Mr. Douglas Adams, that one must think in when considering the universe in its entirety. Weights are measured in yottagrams. Distances are measured in megaparsecs. Most of what we think of as the universe is empty space. When we see the little solar system mobiles, we think of the sun as being a basketball, Jupiter is the bocce ball, and Pluto is the pinball. And there's about a foot between everything. And we tend to think like that all the time, because our minds cannot really digest all the infinity business. We like to think there is a limit, a boundary. We cannot comprehend that there is no final frontier. Let's take the solar system model as an example. Think of your house. It's pretty big, right? Now, how much bigger is a high school? How much bigger is a skyscraper? How many skyscrapers are in New York? How puny is New York compared to Long Island? How puny is Long Island compared to the United States? Think of the small amount of land our country covers. Think of how small the Earth is compared to Jupiter. The Sun is quite a bit larger than Jupiter. Ever seen a basketball that big? Has your brain oozed out of your skull in fright yet?

Once you've understood what sort of scale you need to think in, you can prepare yourself to really sit down and come to terms with this whole universe thing. The basic structure of the universe boils down to this: our local universe (the solar system), our galaxy (the Milky Way), our galactic cluster (the Local Group), and finally, the universe in its entirety.