During the International Year of Astronomy (IYA), there’s no shortage of events and activities revolving around astronomy. Another opened in south-central Wisconsin on Monday, May 4. The Planet Trek Dane County (PTDC) scale-model solar system begins in Madison and extends some 23.5 miles along hiking and biking trails. For those of you in the area who want to get outdoors and appreciate the scale of the solar system, this is a good way to do it.

When solar system models try to fit the scale within a football-field size area, it limits people’s understanding of the sizes. (If Earth is the size of a peppercorn, how do you show Mercury?)

The University of Wisconsin-Madison’s Space Place (astronomy outreach center) designed the scale model with a ratio of 200 million to one. At this scale, Earth is the size of an apple, Saturn is the size of a large beach ball, and Mercury is the size of a walnut. PTDC starts at Monona Terrace on the shore of Lake Monona in downtown Madison. “Pluto” is located in the nearby village of Mt. Horeb.

The installation will remain on display until October 2009 and is open to the public at any time until then. However, if you’d like a guided tour from the UW-Madison astronomy department or the Space Place members, stop by June 20 at 9:00 a.m.

To plan your PTDC bike ride, visit this scalable map of the route. If you’re in the Madison area, stop by the trail.

And remember, there are a bunch of IYA events going on this year. So even if you’re not near Madison, there’s likely some type of astronomy activity near you.