Wednesday, October 07, 2009

Not much time (or weather) left to bike out to Pluto before they pack up the planets


Quick -- if the sun were a sphere represented by a circular flower bed 24 feet in diameter just west of Monona Terrace, how far away would Pluto be, and how big would it be? The answer might surprise you, because most representations of the Solar System are so wildly out of scale. If you actually published a diagram to scale in a book, most of the planets would be invisible.

The answer is that Pluto would be in Mt. Horeb, about 23 miles by bike path from Monona Terrace, and Pluto would be the size of a marble. If it weren't marked by this special sign, you could easily lose it in the grass. The sun, the planets and one asteroid standing in for all the others are all marked by informative signs along the UW Space Place's Dane County Planet Trek Scale Model of the Solar System that's laid out along bike paths all the way to Mt. Horeb. Check out the map at the link.

Physically visiting the sites is a great way to stretch your imagination and develop an appreciation for just how incredibly vast -- and mostly empty -- this little corner of the universe we call the Solar System really is. You might not be up for a bike trip all the way to Mt. Horeb, but you can experience a lot of the impact right within the city limits. All the planets out to and including Saturn are within the Beltline.

So, if the weather picks up a little and makes biking less dreary, you might want to try the inner leg of the journey soon. The display was up all summer, but after October 17 the planets will be packed up for the season. Even the shorter route is filled with surprises and insights. If, for example, Pluto seems incredibly tiny and far away, it's also surprising just how close to the sun Mercury really is.

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