The Ralph Mueller Observatory is open 8:30 to 11pm clear Wednesday evenings September through May. Not sure what viewing conditions will be? There are many resources to help gauge how clear the night sky will be, including Cleveland Clear Sky Chart, Northeast Regional Infrared Satellite, Daylight satellite imagery and the hourly weather forecast. [links on original webpage]
Mueller observatory contains a 10½-inch refracting telescope built by the Warner & Swasey Co. of Cleveland in 1899. The renowned J.A. Brashear Company of Pittsburgh, Pennsylvania, a division of American Optical Company, ground the telescope’s optics. Warner & Swasey Co. originally donated the telescope to Western Reserve College (later Western Reserve University and today Case Western Reserve University). It was located on the roof of the university’s physics building for 61 years.
The Museum acquired the telescope in 1960 with funding from the Murch Foundation. Generous financial contributions from Cleveland businessman Ralph Mueller made the telescope’s installation at the Museum possible.
The telescope rests on an internal support pillar on a block of solid concrete. This construction prevents floor vibrations from reaching the telescope. A 19-foot-diameter dome built by Astro-Dome of Canton, Ohio, houses the telescope. The dome is motor-driven and can be rotated 360 degrees. It has a double shutter, which permits greater sky exposure.
The observatory provides an excellent vantage point from which members of the public are able to observe astronomical events. For example, when Mars made its closest approach to Earth in 50,000 years in 2003, more than 750 visitors viewed the red planet through the telescope on a single evening.