3rd Rock from the Sun is an American television situation comedy with a science fiction undercurrent. The show ran for six seasons on NBC from January, 1996 to May of 2002 spanning a total of 139 episodes. The show was produced by the Carsey-Werner Company and YBYL Productions. The premise of the series involves a group of extraterrestrials who come to Earth to study its cultures. They assume humanoid form and masquerade as a family under the surname Solomon. John Lithgow plays Dick Solomon, the High Commander of the group who helps them to establish their cover identities and encourages the others to go out and see what the planet has to offer. Kristen Johnston plays Sally Solomon, the team's security officer, who is unaccustomed to taking on the form of a female, and must deal with all of the foibles of masquerading as an Earth woman. Joseph Gordon-Levitt is Tommy Solomon who, while assuming the form of a teenage boy is actually the eldest member of the group. Tommy's life becomes difficult when he finds himself struggling with puberty and the tribulations of high school. The team's communications officer, Harry Solomon (played by French Stewart), poses as Dick Solomon's younger brother and is known for his quirky and erratic behavior. He is also responsible for receiving and transmitting message to their superior, the Big Giant Head. Rounding out the cast is Jane Curtin who plays Mary Albright, a human anthropology professor at Pendelton State University in Ohio. She becomes the colleague and potential love interest to Dick Solomon, but is unaware that he and the others are aliens from another planet. Recurring characters on the series include Nina Campbell, Mary Albright's teaching assistant played by Simbi Khali and Mrs. Mamie Dubcek, the Solomons' wacky landlady. Additionally, the students in Dick Solomon's class make regular appearances throughout the series.