A "supermoon" rises above Kansas City, Mo., on Sunday, Aug....

A "supermoon" rises above Kansas City, Mo., on Sunday, Aug. 10, 2014. Forecasters expect the rare showing to be visible to Long Islanders on Sunday, Sept. 27, 2015. Credit: MCT / John Sleezer

With a rare celestial event on tap for Sunday night, Stony Brook University is hosting a moon viewing, opening up its rooftop telescope observatory to the public, a university spokeswoman said.

The sight of interest is a total lunar eclipse, not just of a regular moon, but of a supermoon, the name for full moons that appear supersized as a result of their coming closest to Earth in their elliptical orbit. Supermoons happen about once a year and can appear as much as 14 percent larger and 30 percent brighter than typical full moons, according to NASA.

However, the last time "planetary dynamics" lined a supermoon up with a lunar eclipse was in 1982, and the next one won't arrive until 2033, according to a Nasa.gov post.

Besides the high-powered rooftop telescope, eight other smaller-scale ones will be available for the event to be held atop the Earth Sciences and Space Building and sponsored by the school's Astronomy Club and Japanese Student Organization.

Doors open at 8:30 p.m., with partial eclipse beginning at just past 9 p.m.

Of course, there is a potential glitch, as the weather might not be as cooperative as sky watchers would like.

As of late Friday afternoon, the forecast for the 9 p.m. Sunday to midnight range was for mostly cloudy skies, said Jay Engle, National Weather Service meteorologist based in Upton. But stay tuned, he said, as conditions could change.

Still, clear or cloudy, the event is a "go," the spokeswoman said.

Latest videos