Free Outdoor Discoveryprograms, hosted by the Butler County Parks and Recreation Department, take place Thursday nights at Alameda Park. The program for 7 p.m. today is by Playthings Etc. in the Masonic Shelter. The program June 20 is “Alameda Park: Butler's Disneyland” with Bill May in the Carousel Shelter. There is no program July 4.

The Audubon Society hosts naturalist-led walks at 9 a.m. Thursdays at the Succop Conservancy, 185 Airport Road, Penn Township. Call 412-963-6100 or visit www.aswp.org to register.

McConnells Mill State Park in Slippery Rock Township, Lawrence County, has the historic gristmill open from 11 a.m. to 4 p.m. Fridays, Saturdays and Sundays through October. Interpretive tours of the mill, which last about 45 minutes, will be available at 1 and 3 p.m. Additional tours for groups may be scheduled by calling 724 368-3612. Admission is free.Star parties will start, weather permitting, at 8:55 p.m. Friday and Saturday at the Nicholas E. Wagman Observatory in Deer Lakes Regional Park near Russellton in Allegheny County. Admission is free. Donations are accepted for the costs of operation. Call 724-224-2510.