Employees of the Adler Planetarium announced this week that they have joined a union.

The roughly 80 workers said Tuesday that they have formed the Adler Planetarium Workers United, or APWU, organized by the American Federation of State, County, and Municipal Employees Council 31.

In a letter to their coworkers, the employees said they are concerned about staffing shortages, management communication, and changes to procedures without employees sharing input.

AFSCME Council 31 represents workers at several other major Chicago museums — including the Griffin Museum of Science and Industry, the Field Museum of Natural History, the Shedd Aquarium, the Art Institute of Chicago, and the Chicago History Museum.