PORTLAND — University of Southern Maine officials are planning to cut the physics major, shocking students and prompting professors to vow a fight.

“You can’t call yourself a university if you eliminate something as basic as physics,” Associate Physics Professor Paul Nakroshis said Thursday. “It’s not over.”

On Wednesday, Provost and Vice Chancellor of Academic Affairs Michael Stevenson met with Nakroshis and department Chairman Jerry LaSala and told them to suspend enrollment of new majors immediately and come up with a plan to dissolve the major, incorporating staff and classes into other departments.

Stevenson also said in a memo sent to department heads that the popular Southworth Planetarium, which is part of the physics department, could be closed.

Introductory physics courses, which are needed for many other science degree programs, will continue.

What no longer will be offered are upper-level courses, about four a year, that regularly only have five or six students in them but are necessary for a degree in physics. There are 18 students in the program, which generally graduates three or four students a year. The department has four professors, one of whom is retiring in 2014.

Southworth Planetarium, the only planetarium in southern Maine, attracts more than 17,000 students and community members every year for a variety of programs. University officials said Thursday they intend to keep it open, but Stevenson told the department in the draft plan to “to develop a plan for its use … or recommend its closure.”

Stevenson was not available for comment Thursday.

The next closest planetariums in Maine are at Bates College in Lewiston, the University of Maine in Orono, Maine Maritime Academy in Castine and Lee Academy.

USM President Theodora Kalikow said ending the physics major is simply a financial decision, because the upper-level courses consistently have fewer than 12 students, a baseline for minimum course attendance.

“The financial situation and the academic situation at this campus needs to be addressed,” Kalikow said.

“(Physics) is not the only program we are looking at,” she said. “It’s their turn. There are other programs in different areas, and it will be their turn, too.”

Kalikow declined to say what other programs, or how many other programs, are under review for possible elimination.

“We have to stop doing many things that are unproductive,” she said.

Many students heard the news for the first time Thursday morning.

“Walking around out there, you can tell which ones have heard the news. They all look like they’re in mourning,” said Assistant Physics Professor Julie Ziffer, motioning toward the hallways outside the physics department offices. “They look shocked.”

A handful of physics students doing homework between classes said they couldn’t believe the school would make such a move.

“This is so bad,” said junior Ramses Tamayo, looking up from pages of handwritten formulas scattered on a laboratory table in front of him. Across the table, senior Trevor Hamer agreed.

“Isaac Newton would be rolling in his grave,” Hamer said. “I think it’s ridiculous.”

Nakroshis said he planned to get the Faculty Senate involved and make a case to keep the major, which was created in 1987.

“Don’t worry,” Nakroshis told them. “I’m not going to let it go down without a fight.”

Aside from hurting the university’s ability to attract top instructors and top students, cutting the major doesn’t make sense since the department on average has a large class size and makes money, he said. The introductory physics courses regularly have more than 100 students in them.

“There’s no financial argument,” said Nakroshis, who did a comprehensive review of the department in 2012 when he served as chairman.

Kalikow said the financial concern is linked to professors teaching small numbers of students, not the average class size or department budget.

Ziffer, however, said the decision contradicts an effort touted by state and education officials to get more students involved in the fields of science, technology, engineering and mathematics. She added that physics graduates go on to high-wage jobs and start businesses in the area.

The median annual salary for a physicist is $105,430 per year, according to the federal Bureau of Labor Statistics. Physics is also the basis for a variety of careers in manufacturing, engineering, scientific research, biology and astronomy, among other disciplines.

“We are producing people who contribute, who have high impact,” Ziffer said. Two students in the program now are in the 3-year-old Pioneer Program at USM, which gives a full scholarship to top academic students from Maine.

“I’m worried about being able to get classes,” said freshman Tyler Nelson, a Pioneer Program student double-majoring in physics and mathematics. “I feel like they are pushing around the small majors.”

Small majors and underenrolled classes have been under the microscope systemwide since 2010, when the University of Maine System trustees instituted the so-called “Rule of Five” — that each major should graduate at least five students a year — and the “Rule of 12” — requiring all classes have at least 12 students or be cut.

USM spokesman Robert Caswell said the school cut 47 classes this fall because of low enrollment, including one upper-level physics course that had only four students enrolled. Of the 1,599 undergraduate classes remaining, 187 have fewer than 12 students each.

Physics is not the first big major to be cut under the Rule of Five at USM, Caswell said. German and Russian were cut in recent years because of low enrollment. At the same time, the school has added new majors in sports management and in tourism and hospitality, and a doctorate in nursing practice, since 2009.

Nakroshis, who was chairman of the department last year and has taught at the school for 16 years, said he’s never had upper-level physics courses cut because of low enrollment before this fall.

Under Stevenson’s proposal, the department must respond to the plan by May 31, 2014. The decision to eliminate the major must be approved by Kalikow and then the board of trustees.

The physics department went through the same review and threat of elimination several years ago, but the USM president and provost at the time came to a different conclusion: They recommended the department get more resources.

“Well, of course they came to different conclusions,” Kalikow said Thursday. “It was two, three years ago. That was a different world. It was before frozen tuition, before even more declining enrollments, and before state appropriations were level, at best.

“We have to serve the students in the most effective way with the resources we have,” she said.

The physics department also oversees the popular but money-losing planetarium. LaSala, the department chairman, is also the director of the planetarium.

Planetarium manager Edward Gleason said Thursday he didn’t know of any plan to close the facility and in fact, recent shows such as the current “Dinosaurs at Dusk” show have been among the venue’s most popular draws.

“We’re generally used every day, year-round,” said Gleason, who has managed the site since 1999. “We have concerts, poetry, mythology classes, science classes. It’s very popular, … especially with school groups and for this dinosaur show,” he said, gesturing to the program running on the ceiling.

But the planetarium, which was built in 1970, generally loses between $13,500 and $19,600 a year, Caswell said. Recent shows and aggressive marketing have lessened the losses recently.

Although Stevenson’s memo suggests the planetarium could close, Kalikow said Thursday that the university intends to keep it open.

“I don’t want it to close,” she said. “I want it to be better.”