​Sheldon and Amy to take bold step on "The Big Bang Theory"

Sheldon and Amy are taking their relationship into a bold new frontier on 'The Big Bang Theory" next month.

The on-again, off-again couple will have sex for the first time in an episode taped Tuesday and set to air Dec. 17 on CBS.

"After over five years of dating, we felt the time was right for Sheldon and Amy to finally consummate their relationship, and we're so excited for the audience to see the journey over the next several episodes," executive producer Steve Molaro said in a statement.

Jim Parsons stars as Sheldon Cooper and Mayim Bialik as Amy Farrah Fowler, scientists who are challenged by romance. "The Big Bang Theory," in its ninth season, is TV's top-rated sitcom.

"All these characters work together, even if they're dating, not dating, in a fight -- it kind of works together because this is their social group, whether they're in committed relationships or just figuring it out," Bialik told CBS News in September.

Earlier this year, Parsons received a star on the Hollywood Walk of Fame. "Why I'm specifically here today, the biggest reason, is because I had the chance to play this incredible character that I neither created nor write for nor put into a series," Parsons said.