Neil deGrasse Tyson, director of the world’s most technologically advanced space theater—the Hayden Planetarium, at the American Museum of Natural History, in New York—is the man People magazine voted “Sexiest Astrophysicist Alive.” It’s an unusual claim to fame, for he could not have had too much competition in his field. Then again, in 2007, Time magazine named him one of the 100 most influential people in the world.

This provocative and amusing man is among a rare breed nowadays—a public intellectual popularizing science. With his frequent appearances on The Daily Show and The Colbert Report, as well as his books—the latest one, Space Chronicles: Facing the Ultimate Frontier, published this month by W. W. Norton—the 53-year-old, Harvard-educated Dr. Tyson is consciously building even more bridges between high and popular culture than Carl Sagan did.

“Many academicians don’t even own a television, much less watch one,” he mentioned over lunch in his cluttered office, which looked so disorganized it might have belonged to an unworldly college grad.

I put his knowledge of TV to a little test. “Have you seen Jersey Shore?” I asked.

“Yes, though not as a devoted follower,” he replied.

“Nevertheless, you realize that Snooki is an extraterrestrial?”

“Well, that I did not know! It’s an interesting notion. But I would ask what evidence supports this, other than her testimony.”

The Snooki paradigm is the identical, strictly objective test Dr. Tyson uses for people who claim to have seen flying saucers. “Bring me the physical evidence! Show me a piece of a flying saucer!”

“I got lemonade too,” he said, carrying our lunch trays into his office from the museum cafeteria. “Who doesn’t like lemonade?” There was pea soup and a grilled-cheese sandwich for him, sushi and salad for me.

“When flying saucers land on Earth in sci-fi movies,” I asked, “why do the aliens always exit down a ramp?”

“The flying saucers are handicapped-accessible,” he replied with a straight face.

Dr. Tyson is a paradox of persuasive rationalist and romantic Space Age dreamer. The mystery and ultimate wonder of the universe has awed him since he was a child, raised in the Bronx and obsessed with studying astronomy. No one has ever seen an alien, he agreed, yet he remains confident that intelligent extraterrestrial life exists.

“The universe is almost 14 billion years old,” he explained, “and, wow! Life had no problem starting here on Earth! I think it would be inexcusably egocentric of us to suggest that we’re alone in the universe.”

Stephen Hawking imagines aliens will be malevolent, while Carl Sagan thought they would be friendly, like E.T. “Which is it to be?” I asked.

“I have a third view. The alien is neither evil or kind. What if he’s just much smarter than us? The closest animal to us is of course the chimp. There’s a trifling difference in our DNA of less than 2 percent. The urge is to say what a difference that makes. But take a different tack: We know that the smartest chimps are able to accomplish what our toddlers can do. So imagine there’s another life-form on Earth, or aliens, that are 2 percent beyond us in intelligence. It would mean their alien toddlers can do what the smartest of us can do. They would see the Hubble telescope as a quaint little exercise they do in their shop class in first grade!”

“If they’re so clever, why don’t they invade Earth and conquer us?”

“In this scenario, they could enslave us and we wouldn’t even know it. But I wonder whether we’re simply uninteresting to them—as uninteresting as a colony of worms you walk past on the street.”