On the season 1 episode entitled “The Peanut Response,” Penny (Kaley Cuoco) decides to throw Leonard (Johnny Galecki) a shock birthday celebration. Whereas she’s making an attempt to persuade Leonard that he ought to rejoice his birthday by going to the Cheesecake Manufacturing unit, Penny and Sheldon get into an argument about birthdays on the whole. Unsurprisingly, the scientist has little interest in celebrating them, and does not really feel like Penny ought to drive Leonard into celebrating his both.

Realizing she will not win an argument towards Sheldon, Penny, who had beforehand calculated virtually all the guys’ astrological indicators and deliberate to do their horoscopes, finally hits again with, “Blah, blah, blah — “typical Taurus.” Being a Taurus would put Sheldon’s birthday someplace between April 20 and Could 20. However there’s truly one thing very mistaken with Penny’s assertion right here.

There’s little point out of it once more, contemplating Sheldon’s stance on birthdays. That’s, till The Large Bang Principle season 8. On that season, Penny once more refers to astrology (one other factor Sheldon despises), however this time she calls him a Pisces, which might put his birthday between February 19 and March 20. Because it seems, Sheldon is a Pisces, with the 200th episode of the collection, “The Celebration Experimentation” from season 9, revealing his birthday to be February 26 when Amy (Mayim Bialik) determined to throw him a birthday celebration, a lot to his dismay. Additional affirmation got here from The Large Bang Principle‘s official Twitter web page in 2016, when the account inspired followers to want Sheldon joyful birthday in February.