When the city lights hide the galaxy stars, space observation is difficult for city dwellers, but two Boston observatories offer free stargazing on clear nights through late November. The public can use the Museum of Science’s Gilliland Observatory on Friday nights from 8:30-10 p.m. Call the observatory hotline, 617-589-0267, for information about that night’s session. The Coit Observatory at Boston University, pictured, hosts a public open night every Wednesday beginning at 7:30 or 8:30 depending on the season.

Wednesday and Friday nights; Free