AN OVERFLOW CROWD: Excitement about the upcoming solar eclipse made for a packed house at the first of two lectures, held at Princeton Public Library. Next on the eclipse agenda is a special viewing party on Palmer Square on Monday, August 21.

It was standing room only last week in the Community Room at Princeton Public Library, where Princeton University professor Amitava Bhattacharjee was giving a talk on the once-in-a-lifetime solar eclipse that will unfold over several hours on Monday, August 21. 

Children were crowded up front, seated on the floor. The adult overflow stood along the walls and the rear of the room. “It was all ages, from 8 to 80,” said public programming librarian Janie Hermann, who planned the event with technology instruction librarian Kelsey Ockert and the University’s Department of Astrophysical Sciences.

It is probably safe to assume that the same crowd, along with hundreds of others, will be at Palmer Square on Monday for the Solar Eclipse Viewing Party, which starts at 1 p.m. and includes activities at six stations, a countdown clock, and lots of watermelon and Oreo cookies. Why Oreos? “So you can practice making an eclipse with your cookie before you eat it,” said Ms. Hermann, who has been planning the party with colleagues from the library and University since April.

“We knew a year ago that this was going to happen, and there was a big push from the entire library community,” she continued. “We wouldn’t be able to do it without our partnership with the astrophysics department of the University, especially Fred Moolekamp and his team. They are doing all of this free of charge.”

The physicists will be on hand to answer questions, show demonstrations and models, and prepare the crowd for the spectacle of the moon temporarily blocking the sun as it moves between the Earth and the sun. While Princeton viewers won’t witness the sun being completely covered, as in “totality,” there will still be a show. Only a small swath of the country, extending across 14 states, from the Northwest to Southeast, will be completely darkened.

In Princeton, expect about three quarters of the sun to be blocked by the eclipse. The peak is expected about 2:45 p.m., and will last about two minutes. The sun will slowly become visible again after that, and the eclipse should end by 4 p.m. in this part of the country.

“This is a unique and historic event, and the library wanted to make sure that those who were unable to travel to the path of totality had an opportunity to come together as a community and learn more about what would be happening that day,” said Ms. Hermann. “We wanted to make it memorable for people of all ages. We will get to about 77 percent totality, and our team at the University says it should be a good show.”

Viewing the eclipse comes with certain precautions. Astronomy experts warn people not to look directly at the eclipse — before, during, or after — unless they are wearing proper eclipse glasses, with the right kind of solar filters. Forgoing the special glasses can result in serious damage to the retina. Experts advise using glasses that have a logo resembling a globe, and the letters “ISO” and “CE,” which are those that have been tested and declared safe.

The library has glasses that meet the requirements. Some 350 pairs have been distributed and another 400 will be handed out at the viewing party. “Somebody at Princeton University knew somebody at Google who sent us all of these glasses,” said Ms. Hermann, who added that those who have their own pairs at home are encouraged to bring them to the gathering.

Party planners went back and forth about the best location for the event. “It was a big decision. We wanted someplace central and had thought of the roof of the Spring Street Parking Garage, but worried it might be too hot,” Ms. Hermann said. “We also thought about Hinds Plaza, but there is a lot of tree cover. We considered fields on the University campus. The biggest consideration was that there be tree cover for people to stay cool, but enough open space to see the eclipse. Palmer Square was the best place because it has trees, a lawn, and enough open space.”

The party will go on for three hours as the eclipse progresses. A crossword puzzle, coloring sheets, and other activities will keep children engaged. “The astrophysical department team will line up the kids and recreate the solar system,” Ms. Hermann said. “They have grad students and faculty coming out, and we have teen volunteers.”

The event is free and open to the public. “We want people to feel like they were a part of it, even though we are not in the path of totality,” Ms. Hermann said. “It won’t be the whole show, but it will definitely be a show.”