The next day, she said, as she was driving Dr. Tyson home from work, which was part of her job, he told her, “You say you want to be a producer, but it’s always going to be an uphill battle for you because you’re too distracting.”

The next day, she told a supervisor what had happened, and that she had to quit. The supervisor, a line producer, asked Ms. Watson if she wanted to file a complaint, and she said no, she said. After that, the supervisor suggested she tell her co-workers that she was leaving because of a family emergency. She left the show.

In his Facebook post, Dr. Tyson described the handshake as one he uses “in appreciation of people with whom I’ve developed new friendships.” He said that at work, Ms. Watson freely offered hugs, which he typically rejected, but that on a few occasions, he “clumsily declared, ‘If I hug you I might just want more.’”

“My intent was to express restrained but genuine affection,” he wrote.

He wrote that Ms. Watson had come into his office after the night in his apartment and told him she had been “creeped out.” He said he had “apologized profusely” and that she had accepted the apology.

Another woman, Katelyn N. Allers, an associate professor of physics and astronomy at Bucknell University in Pennsylvania, told Patheos about meeting Dr. Tyson in 2009 at a party after a gathering of the American Astronomical Society. Dr. Allers has a tattoo of the solar system stretching from an arm to her collarbone. She said Dr. Tyson was “obsessed” with whether the tattoo included Pluto. “He looked for Pluto, and followed the tattoo into my dress,” she told the website, describing it as “uncomfortable and creepy.”

In his post, Dr. Tyson noted that Pluto had been declared no longer a planet just three years earlier, “so whether people include it or not in their tattoos is of great interest to me.” He said he did not know until now that Dr. Allers had been uncomfortable. “That was never my intent and I’m deeply sorry to have made her feel that way,” he wrote.