Yet in 1990, shortly after he celebrated 10 years as the university’s president, Dr. Berendzen resigned in scandal, shocking colleagues with the revelation that he had been making obscene calls from his campus office.

While using a fake name and identifying himself as a psychiatrist, he had talked with strangers about incest and child abuse, spinning elaborate sexual fantasies involving a fictitious 4-year-old girl that he said he had caged in his basement.

The disclosures appeared to have shattered his reputation and ended his career. Yet after spending nearly a month in psychiatric treatment, revisiting traumatic memories that he said he had spent years trying to forget, Dr. Berendzen reestablished himself as a voice for survivors of childhood sexual abuse, eventually returning to American University as a professor.

As he told it, he had made the obscene calls out of a misguided effort to work through memories of childhood sexual abuse. He initially declined to name his abuser before publishing a 1993 memoir, “Come Here: A Man Overcomes the Tragic Aftermath of Childhood Sexual Abuse,” that identified the perpetrator as his mother, a homemaker who had struggled with mental illness and was briefly institutionalized when he was a child.

“The person on the other end of the phone turned out to be, essentially, a surrogate for my own victimizer,” Dr. Berendzen said in a 1990 interview on ABC’s “Nightline.” “It was as if I were having a conversation with the person that I both trusted and loved and hated and despised and was victimized by, all at the same time.”

Dr. Berendzen, who also worked as a consultant to NASA and sought to popularize astronomy in books and interviews, was 84 when he died Nov. 3 at his home in Arlington, Va. He had not wanted his death publicized, said his wife, Gail Berendzen, when reached by The Washington Post after a former student notified the paper of Dr. Berendzen’s passing. The cause was complications from a respiratory ailment, she said.

When Dr. Berendzen was appointed president of American University in 1980, the institution was struggling with low morale and a poor financial outlook, and was trying to shed its reputation as a party school that students called “Camp AU.”

Dr. Berendzen, who had arrived at the university in 1974 as dean of the College of Arts and Sciences and was named provost two years later, sought to raise its academic standards and turn the school into “a national university,” as he put it.

He started small, ordering workers to repaint buildings and plant azaleas around the quad. Then he set about raising admissions standards, fighting grade inflation, constructing new buildings and doubling down on the university’s strengths, expanding some departments while trimming others.

Applications to the school increased, as did the average SAT scores of incoming freshmen. By the end of his tenure, the school’s endowment had quadrupled, growing from $5 million to $20 million.

“It was almost a hitch-your-wagon-to-a-star philosophy. He convinced us, ‘You just follow me and it’ll happen,’” said Valerie Morris, chair of the university senate, in a 1990 interview with The Washington Post. “And one thing at a time, it happened.”

To promote the school, Dr. Berendzen spoke at public events across the country and gave hundreds of interviews a year. He also made a point of attending glitzy Washington parties where he mingled with Walter Cronkite, Jacqueline Kennedy Onassis, the Dalai Lama and President Ronald Reagan. A few of his new acquaintances, including business leaders John W. Hechinger and Forrest E. Mars Jr. were brought on to the board of trustees, which Dr. Berendzen claimed was the wealthiest of any university in the nation.

Although the school rose in prominence, some critics labeled Dr. Berendzen a self-promoter, questioning the behavior of a president who once arrived at a contentious faculty meeting wearing a suit of armor. They also condemned his association with figures like Adnan Khashoggi, a Saudi arms dealer implicated in the Iran-contra affair, whom he brought on as a trustee.

Rumors circulated that Dr. Berendzen’s frequent media appearances were auditions for another, loftier role, potentially in the U.S. government, although Dr. Berendzen insisted he was focused on the job at hand.

“Except for my family, I live for little else than the institution,” he wrote in a 1986 memoir, “Is My Armor Straight?: A Year in the Life of a University President.”

But two years later, after his father died, Dr. Berendzen returned to the family home in Dallas. He saw the bedroom where he was first sexually abused at age 8, beginning a cycle of mistreatment that lasted, by his account, until he was 12. The visit left him increasingly preoccupied by painful memories, and after he returned to Washington he began making obscene calls, finding phone numbers in the newspaper for people who advertised child care in their homes.

One woman he called in March 1990, Susan Allen, happened to be married to a Fairfax County police officer. When she realized that Dr. Berendzen was not who he claimed to be, she decided to try to help the police catch him. Investigators installed a tape recorder and call-tracing device on her phone, and within a few weeks the calls were traced to Dr. Berendzen’s office. He was confronted by the school’s board of trustees, offered his resignation and checked himself in to the sexual-disorders clinic of Johns Hopkins Hospital in Baltimore.

That May, he pleaded guilty to two misdemeanor charges of making obscene phone calls. He was sentenced to two 30-day jail terms, suspended on the condition that he continue psychiatric counseling for a year. A report from his treatment team had concluded that he was “not a pedophile,” and that his obscene calls were an attempt at “seeking answers to unresolved issues related to his own abuse.”

That finding was met with skepticism by some, including Allen, who questioned whether Dr. Berendzen had been trying to do damage control by sharing his account of childhood abuse. She filed a reported $15 million lawsuit against Dr. Berendzen and AU, citing emotional distress, and settled out of court, according to People magazine.

Dr. Berendzen went on to work with survivors of childhood sexual abuse, including as a board member of nonprofit organizations that deal with child-protection organizations. He still found it difficult to discuss the topic, and was eager to focus on astronomy instead. Asked about the abuse and the pain that still lingered, he told talk-show host Larry King in 1993, “I would much rather talk to you about the birth of the universe.”

Richard Earl Berendzen, an only child, was born in Walters, Okla., on Sept. 6, 1938. The family soon moved to Portland, Ore., where a young Dr. Berendzen struggled with rheumatic fever and asthma. In search of a drier climate, he and his parents moved to Dallas, where his father got a job as a hardware store manager.

Dr. Berendzen continued to suffer health issues, and told The Post that he was bedridden for three years before starting school in the second grade. He found solace stargazing on his lawn, staring upward at the constellations and wondering whether life might exist on some distant planet.

He earned a scholarship to Southern Methodist University, where he studied physics, and transferred to MIT after his sophomore year, graduating in 1961. At Harvard, he studied astronomy and education, serving as a teaching assistant to Carl Sagan and earning a master’s degree in 1967 and a doctorate in 1969.

Two years later, he was named chair of the astronomy department at Boston University, where he taught before joining AU.

An early marriage to Barbara Edwards, his high school sweetheart, ended in divorce. In 1964, he married Gail Edgar. In addition to his wife, survivors include a daughter from his first marriage, Deborah; a daughter from his second, Natasha; and two grandchildren.

Dr. Berendzen co-wrote books, including “Man Discovers the Galaxy” (1976) and also released a nine-hour audiobook, “Pulp Physics” (2000), that explored the history of science and inspired science-fiction sequences in the film “Another Earth” (2011), starring Brit Marling and William Mapother. Dr. Berendzen served as a consultant on the film and provided narration, employing a voice that director Mike Cahill once described as “Darth Vader meets God.”

After the phone-call scandal, he taught at AU from 1992 until 2006, when he retired as a professor emeritus. He also directed NASA’s Space Grant Consortium for Washington, which offers fellowships in science and math. He had previously served on a space exploration advisory task force for the agency.

Discussing space travel and science, he could be philosophical, as when he spoke with ABC News’s Ted Koppel in 1996. “I would like to believe that with the discovery of even a simple fossil of a bacteria on Mars, it would teach us what we ought to know all along,” he said, “and that is that what bonds us here on Earth, all of the diverse peoples here, really is much more profound than what seems to separate us.”