Like sports arenas, arctic igloos, and capitol buildings, planetariums are usually domed structures with a propensity for laser beams. Experience glorious rays in an embowed setting with today’s Groupon: for $10, you get two Friday or Saturday evening admissions to the planetarium (a $7 value for each adult ticket) or laser show (a $10 value for each adult ticket) at the Vanderbilt Museum in Centerport (up to a $20 value). This Groupon expires on July 30.

Connected to William K. Vanderbilt II’s 24-room mansion, the 60-foot domed planetarium seats 238 in the Sky Theater, using a Goto star projector and dozens of perimeter slide projectors to display 11,369 stars. Settle in at 8 p.m. to see Journey Through the Solar System, a visually and audibly engaging look at the history, contents, and personality flaws of our beloved solar system, as well as its most ardent explorer, NASA. A video library and laser disks supplement stationary images with moving pictures, an effect that makes the universe and time seem to fly by. Afterward, examine the meteorites and 6-foot-wide moon globe on display in the lobby.

Each Friday and Saturday evening schedule also features multiple laser light displays set to the popular tracks of such rock legends as Aerosmith, The Beatles, and Pink Floyd. Ears are treated to a carefully arranged cacophony of sound and eyeballs follow the rhythmic flashes of strobe and videos on the domed screen until onlookers have turned into walruses.