The big bang theory
Cast of the hit CBS show The Big Bang TheoryCBS

The Big Bang Theory season 8 will return with an all new episode this Thursday, 8 January on CBS.

The 12th episode is titled, The Space Probe Disintegration, where Sheldon and Leonard will have a heart-to-heart conversation.

The official synopsis reads as follows:

When the guys finally agree to do something the girls like, it leads to a confrontation between Leonard and Sheldon. Wolowitz tries to distract Raj, who is anxiously awaiting data from a space probe he helped launch. Meanwhile, Sheldon and Leonard go dress shopping with Penny and Amy,

However executive producer Steve Molaro has said that the writers "aren't in a rush for a Leonard and Penny wedding".

Molaro told Tvline that the upcoming episodes will focus on the finer points of the couple's engagement like, "future living arrangements regarding Sheldon."

Also, in the next episode will pay a tribute to Carol Ann Susi, the late actress who voiced Wolowitz's mother.

"The death of Carol will be dealt with," Molaro added.

"We just needed time to process the loss of our friend."

As for Sheldon and Amy's slow-burn relationship, there are no immediate plans for the two to tackle another milestone after the love surprise was dropped in November.

"We are discovering the show, the relationships, the problems, as we go along. It's more a discovery process than a planning one," Molaro concluded.