aired for more than a decade, from 2007 to 2019. During that time, it quickly became one of the viewer’s favorite sitcoms. Now, three years after last episode came out, fans are still learning new things about the show like, for example, that many stars, including , auditioned for the role of Penny before .

In addition to this, it was recently revealed that had many big stars in mind to take the role of Amy’s step-sister in the series’ last seasons.

In fact, they even tried to convince to play this part, but the singer ultimately rejected the role. It is well known that the was a huge fan of , so why didn’t she appear on the show?

The Big Bang Theory Was CBS’ Most Popular Sitcom

premiered on CBS on September 24, 2007, and concluded on May 16, 2019, having broadcast more than 270 episodes over a total of 12 seasons. Believe it or not, the show received mixed reviews throughout its first season, but its reception among viewers was a huge success.

Slowly but surely, gained tons of popularity. By 2012, it was number two in terms of ratings, and it ultimately reached the number one ranking in its eleventh season. By the time it ended, had become the of all time.

After the success of the show, it’s no wonder that CBS decided to create a about the childhood of the fan-favorite character, Sheldon Cooper.

In addition to high rankings, and its cast won numerous awards. The show won seven Emmy Awards from 46 nominations, including Emmy Award for Outstanding Lead Actor in a Comedy Series four times for .

A Recently Published Book Dives Into All The Secret Behind The Making Of This Popular Sitcom

After ended, Jessica Radloff published her book . Thanks to this, fans have been able to learn many new things about this beloved sitcom.

For example, in Radloff’s book, it was revealed that Jodi Lyn O'Keefe had been originally cast to play Penny. The actress, better known for playing Cassidy Bridges in the television series Nash Bridges, even filmed an unaired pilot with Jim Parsons and Johnny Galecki.

Ultimately, O’Keefe was fired from the show because . After that, other actresses, including Marisa Tomei, Elizabeth Berkley, Tara Reid, and Amanda Walsh, auditioned for the role. But, ultimately, the role was rewritten and given to Kaley Cuoco.

Another big secret that was revealed in this book was that, originally, the creators of the show wanted to break up one of the show’s main couples! Bill Prady admitted that Penny and Leonard almost didn't end up with each other, but the writer ultimately decided against it.

Selena Gomez Was Offered The Role Of Amy’s Step-Sister On The Big Bang Theory

Turns out that Selena Gomez is a big fan. Back in 2016, the star posted a picture of herself watching the hit CBS show on her laptop before her concert in Nashville, Tennessee, on her Instagram account. The caption read: "The one thing that gets me going before anything... Sheldon Cooper -- Big Bang Theory."

Thanks to Radloff’s book, fans now know that Selena Gomez was offered a small role in . Before it was established that Amy (Mayim Bialik)’s parents were still together, the writers of the show had an idea for an episode in which Amy complained about her awful step-sister. They wanted Selena Gomez to play this part and be so beautiful and great that everyone would love her.

Unfortunately, this was not possible because the star had a busy schedule that conflicted with filming for the show.