Stargazers can see celestial objects such as the dumbbell galaxy and the ring galaxy through the telescopes, as well as a bevy of other celestial objects.
The sky looks like it should be fairly clear Friday and Saturday night, though clouds may start moving into the area late Saturday, said Eric Schoening, forecaster for the National Weather Service.
Temperatures will likely be in the 50s or high 40s, Schoening added.
That makes it important to dress warmly, said Joe Bauman, SLAS vice president.
A drawing for kids ages 5 to 18 will be held, and astronomy books and telescopes will be given as prizes.
While this weekend marks the last planned star party of the season, the society's president, Rodger Fry, said that if Comet ISON turns out to be as eye-popping as earlier reports indicated, the observatory may reopen in late November for the comet show.
Currently, the comet is not as bright as first predicted, Wiggins said, but that could change.
A comet's brightness is determined by the elements it is made of and its position in relation to the sun. If the right elements compose the comet's nucleus, which is usually 2 or 3 kilometers across, they will sublimate (turn from solid to gas quickly) and create a large coma of gas that can be as large as a planet. Then, the pressure from the sun, called the solar wind, pushes on that gas cloud, creating the comet's tail. That's why a comet's tail always points away from the sun, regardless if the comet is heading toward or away from the sun.
However, if the comet gets too close to the sun, the nucleus can explode in a bright explosion or simply evaporate, Wiggins said.
"I'm hopeful the conditions will be perfect and it will be great viewing," he said, "but Kohoutek looms large in my mind."
That comet was sighted in 1973 and was touted as being a spectacular "comet of the century" that ended up being a letdown when it disintegrated before brightening well enough to see it.
"We don't want to raise false hopes," Wiggins said.
But he and the rest of the astronomical community have been watching ISON as it approaches the sun, hoping it will continue to brighten enough to see with binoculars or even the naked eye.
"At this point, I'm less encouraged than I was at the beginning," Wiggins said. "But it's just that we don't know."
How to get to Stansbury Park Observatory Complex
To reach the Stansbury Park Observatory Complex from Salt Lake City, take Interstate 80 west and leave the freeway at the Tooele-Grantsville turnoff, Exit 99. Continue south until the third traffic light. There, at a Maverik store, turn right (west) onto a side road and continue a short distance into Stansbury Park and follow the signs to the observatory. Take a left into the parking lot. The observatory is west of the parking area, just beyond a skateboard park.