LOS ANGELES - National Geographic Channel has pulled its long-running Neil deGrasse Tyson chat show, "StarTalk," off the air, at least for now, following allegations of sexual misconduct against the famed astrophysicist. "StarTalk" will remain on hiatus as a Fox Networks Group investigation into the multiple claims continues.

"In order to allow the investigation to occur unimpeded we chose to hold new episodes of 'Star Talk' until it is complete," a Nat Geo rep told Variety. "We expect that to happen in the next few weeks at which time we'll make a final decision."

"StarTalk" returned for its fifth season in November and had aired just three episodes, out of a 20-episode order, when new allegations against Tyson emerged. The website Patheos reported that two women had accused Tyson of inappropriate behavior: Bucknell University's Dr. Katelyn N. Allers claimed Tyson groped her at an event in 2009, while a former assistant, Ashley Watson, said Tyson made repeated inappropriate sexual advances toward her.

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This wasn't the first time Tyson had been accused of misconduct; musician Tchiya Amet has claimed that Tyson raped her when they were both graduate students in the 1980s.

"Star Talk" was scheduled to air original episodes through December and up until now, but hasn't been seen on Nat Geo since November 26. The StarTalk page on Nat Geo's website features the first three episodes of Season 5, but makes no mention of the show's current hiatus.

The timing of the allegations put Nat Geo in a tough position. Not only had it just promoted the return of "StarTalk," but its much-anticipated 13-episode series "Cosmos: Possible Worlds," the latest edition of the "Cosmos" revival hosted by Tyson, is set to premiere on March 4.

"Cosmos: Possible Worlds" will also air on the Fox network, premiering on March 3, the night before its Nat Geo launch. With just two months before air, it would be virtually impossible for Fox and Nat Geo to replace Tyson on "Cosmos." Not only does he narrate the series, but he's incorporated on-camera throughout the show. Nat Geo has touted the fact that "Cosmos: Possible Worlds" will air as a global event on National Geographic in 172 countries and 43 languages, making it an important centerpiece for the network. Should Fox and Nat Geo opt to part ways with Tyson, it would require time and effort to recut the show with a new host (such as, say, executive producer Seth MacFarlane).

Late last year, after the latest allegations, Fox and Nat Geo released a joint statement: "We have only just become aware of the recent allegations regarding Neil deGrasse Tyson. We take these matters very seriously and we are reviewing the recent reports." The show's producers, which include Ann Druyan's Cosmos Studios and MacFarlane's Fuzzy Door Productions, said in a statement last month that they "are committed to a thorough investigation of this matter and to act accordingly as soon as it is concluded."

For his part, Tyson denied the allegations in a Facebook post, and said he welcomed an investigation: "In any claim, evidence matters. Evidence always matters. But what happens when it's just one person's word against another's, and the stories don't agree? That's when people tend to pass judgment on who is more credible than whom. And that's when an impartial investigation can best serve the truth - and would have my full cooperation to do so."

Since then, Tyson has canceled several talks he had planned to give this month in Orlando, Jacksonville, and Boca Raton, Fla.

The "Star Talk" episodes that have already run featured guests including the late Anthony Bourdain, comedian Joe Rogan, and "The Big Bang Theory" star Simon Helberg. Episodes in the can and waiting to air include guests George R.R. Martin, former Vice President Al Gore, Weird Al Yankovic, Bill Nye, Dan Rather, Jeff Goldblum, Jack Black, James Marsden and Anna Deavere Smith.