From Murchison Road, turn right (if heading away from downtown) or left (if heading towards downtown) at the light for W.T. Brown Drive (the main campus entrance). Go up the hill, and the last building on the left before you reach the stop sign is the Lyons Science building (it is the building without the brick facade).
If you are driving a school bus, as soon as you go to W.T. Brown Drive, make the first right. As soon as you get past the first building on the right, which is Seabrook Auditorium, turn right into the parking lot. Follow the campus police directions on where to park there. Then have your students go back to W.T. Brown and walk up the hill to the Planetarium.
If you are driving a personal vehicle, it must be registered on campus. If you are an individual family who would like to join an existing show, proceed to the first stop sign after the Lyons Science building (just before the railroad tracks) and turn left to M. L. King Drive. After crossing a red brick crosswalk, go to the second building on your left. This is the Mitchell building, where the campus police are. Bring your vehicle registration and follow their instructions on where to park. Allow at least 15 minutes to get your vehicle registered (vehicle registration is free).
If you are driving personal vehicles for a scheduled show (such as a homeschool group), you do not need to register your vehicles individually; the planetarium director would have already notified the police. Just park in the lot behind Seabrook Auditorium, where the school buses would park.