The Frederick P. Rose Director of the Hayden Planetarium, Neil deGrasse Tyson, recently spoke on his memoir “The Sky Is Not the Limit: Adventures of an Urban Astrophysicist” (Prometheus Books) at the American Museum of Natural History.

Mr. Tyson said that the lecture was going to be an experiment. The museum offers hundreds of programs a year from which audiences may learn about the “beauty, grandeur, and splendor of the universe.” By contrast, Mr. Tyson said he would recount a story on a different scale: He planned to tell the tale of one boy growing up in the Bronx and becoming a scientist.

When astrophysicists share their theories with colleagues, monologues often ensue, he said. But if asked how the same scientists chose their profession, their “answers tend to be much shorter.” One example of such a response: “Well, I was good at math.”

Mr. Tyson did not let himself off the hook so easily. He thanked his parents for exposing him to the myriad offerings in the city and recalled visiting the Hayden Planetarium as a 9-year-old. He remembered tracking the movement of the stars from his Bronx rooftop. He did so with his first telescope – paid for by walking dogs at 50 cents a stroll.

Appropriate to the recent spate of wintry weather, Mr. Tyson recounted a tale from his senior year of high school. A snowball fight erupted in the schoolyard, and he inadvertently hit one of the school toughs – a noncombatant: “a most unfortunate incident.” When the student pulled out a knife with a 6 1/2 inch blade, Mr. Tyson said to the audience, “I never thought that scene in West Side Story was ever real.” Although Mr. Tyson was captain of the wrestling team and knew martial arts, he told his fellow student that he was sorry. “I didn’t throw it at you on purpose. I don’t expect this will ever happen again,” he recalled saying.

But back to space. As a graduate student at Columbia University, Mr. Tyson was assigned to answer cold calls that came to the department from the public. One day, Fox News called about an explosion on the sun and inquired about a “big blob of charged particles headed towards earth.” The news reporter asked, “Is this bad?” Mr. Tyson soothed the reporter’s fears by explaining that the sun “burps” occasionally, causing charged particles to spiral down and hit Earth’s atmosphere. The phenomenon results in a display of the Northern Lights. “Go north,” Mr. Tyson said.

He was invited to say that on air. “We’ll send a limo up to get you,” the reporter offered.

The television appearance eased long-held guilt on Mr. Tyson’s part. A fellow student-wrestler had once chastised his career choice, saying, “The black community cannot afford the luxury of having someone of your talent spend their life on astrophysics” when issues of poverty and injustice were more pressing than Pluto and other cosmic matters. “He can’t be right,” he recalled thinking.

His experience on-air made Mr. Tyson realize how rarely black people are on camera – other than entertainers – offering expertise on issues other than race. He realized he could help society overcome racial stereotypes and fight the last lingering barriers to mutual respect for each other.

Mr. Tyson discussed race in other contexts. For example, he was once stopped by a security guard while bringing physics books into a building. He deadpanned that security seldom stops blacks from walking into a campus gym at night. He also recalled trading police stories with other faculty at a gathering of National Society of Black Physicists and commiserating over the difficulty of catching a cab as an African American heading north to Columbia. He would get one going south and then ask it to turn around.

Mr. Tyson expressed his belief that having a role model was generally an overrated concept. He said he had not looked for “other black astrophysicists born in the Bronx,” but rather assembled his role models a la carte.

He said the best teachers were ones who made a difference in someone’s life, such as those who get a failing student to boost their grade to a C. The best teachers are not necessarily those who boast they have several “straight-A” students; for, all the other teachers are giving them those grades, too. It may be the students’ ability, and not the teacher, making the difference.

The best teachers, he said, are those with passion, who are able to interest the student “in stuff you didn’t care about before.”