PASADENA, Calif. (AP) — Astrophysicist Neil deGrasse Tyson says his Christmas tweet about Isaac Newton shouldn't be interpreted to mean he's anti-Christian.

Tyson, who will host a new late-night talk show on the National Geographic Channel starting in April, attracted attention for tweeting on Dec. 25: "On this day long ago, a child was born who, by age 30, would transform the world. Happy Birthday Isaac Newton b. Dec. 25, 1642."

It was retweeted some 80,000 times, or about 40 times more than his typical messages are shared.

He said Wednesday that he was trying to give people a cosmic perspective, and wasn't trying to insult Christians.

"We know Isaac Newton was born on Christmas Day," he said at a television conference. "Who knows when Jesus was born?"

He said he was surprised that his tweet seemed to hit a nerve.

"It's free speech, so I'm an observer of this, almost as an anthropologist," he said.

Tyson's new show, "Star Talk," will be the National Geographic Channel's first late-night series. It's based on his podcast that tries to mix pop culture with science. The show will be taped before a studio audience at the American Museum of Natural History's Hayden Planetarium in New York, the network said.

"We bring science to people who didn't know they liked science, or thought they didn't like science," he said.