‘The Big Bang Theory’ cast at Griffith Observatory

The cast from ‘The Big Bang Theory’ takes in the daytime view at Griffith Observatory. From left: Mayim Bialik, Jim Parsons, Johnny Galecki, Kaley Cuoco, Kunal Nayyar, Simon Helberg and Melissa Rauch. (Ricardo DeAratanha / Los Angeles Times)

June 5, 2013 4:36 PM PT

The stars from ‘The Big Bang Theory’ joined Times staff writer Glenn Whipp at Griffith Observatory to talk about the success of their show, which recently hit the 20-million-viewer mark.

'The Big Bang Theory' at Griffith Observatory

The cast gets the point of being seated with a statue of Albert Einstein. (Ricardo DeAratanha / Los Angeles Times)

Melissa Rauch, who plays Bernadette on the show, at the Envelope Round Table discussion. (Ricardo DeAratanha / Los Angeles Times)

Kunal Nayyar is astrophysicist Rajesh “Raj” Koothrappali on the CBS sitcom. (Ricardo DeAratanha / Los Angeles Times)

Mayim Bialik, who plays neurobiologist Amy Farrah Fowler, with Kunal Nayyar at the Round Table chat. (Ricardo DeAratanha / Los Angeles Times)

Jim Parsons has won two Emmys and a Golden Globe for his portrayal of theoretical physicist Sheldon Cooper on “The Big Bang Theory.” (Ricardo DeAratanha / Los Angeles Times)

The characters of Jim Parsons and Mayim Bialik have a growing relationship on the show. (Ricardo DeAratanha / Los Angeles Times)

Mayim Bialik says of the Sheldon-Amy story: “The fun thing about our characters is that they’re both missing the filter for social propriety. It’s sweet.” (Ricardo DeAratanha / Los Angeles Times)

Johnny Galecki, Leonard Hofstadter on the show, says word of mouth got the series rolling. (Ricardo DeAratanha / Los Angeles Times)

Kaley Cuoco, who plays waitress and neighbor Penny, with Johnny Galecki and Simon Helberg, whose character, Simon Wolowitz, is a newlywed aerospace engineer. (Ricardo DeAratanha / Los Angeles Times)

Simon Helberg says he hears from people who watch the show in syndication at dinnertime as a family thing. (Ricardo DeAratanha / Los Angeles Times)

Director Mark Cendrowski, left, and producer Steve Molaro join in the Round Table discussion of “The Big Bang Theory.” (Ricardo DeAratanha / Los Angeles Times)