Enter VPM high school from the large parking lot on the corner of Mineral Point and Gammon Road through the doors under the awning. Signage and arrows will guide you to the planetarium entrance (left, right, up a few stairs, slight left... you are there!).
The closest entrance is door #3 on the Gammon Road side of the building, near the flagpole and main school sign. Enter and the planetarium entrance is right there!