“As many intelligent people know, aliens are all around us. This is a story of a band of four such explorers. In order to blend in, they have assumed human form. This is the High Commander (Dick Solomon). He has assembled an elite team of experts: A decorated military officer (Sally Solomon), a seasoned intelligence specialist (Tommy Solomon) and, well, they had an extra seat (Harry Solomon).”

3rd Rock from the Sun (sometimes referred to as simply 3rd Rock) is an American sitcom that aired from 1996 to 2001 on NBC. The show is about four extraterrestrials who are on an expedition to Earth, which they consider to be the least important planet. (Earth is the third planet from the sun.) The extraterrestrials pose as a human family in order to observe the behavior of human beings.

The premise of the show revolves around an extraterrestrial research expedition attempting to live as a normal human family in the fictional city of Rutherford, Ohio, said to be 52 miles (84 km) outside of Cleveland, where they live in a loft apartment. Humor was principally derived from the aliens' attempts to study human society and, because of their living as humans themselves while on Earth, to understand the human condition. In later episodes, they became more accustomed to Earth and often became more interested in their human lives than in their mission.

Dick Solomon (John Lithgow), the High Commander and leader of the expedition, is the family provider, and takes a position as a physics professor at Pendelton State University. Information officer Tommy (Joseph Gordon-Levitt) has been given the body of a teenager and is forced to enroll in high school (later college), leaving security officer Sally (Kristen Johnston) and communications officer Harry (French Stewart) to spend their lives as thirty somethings hanging out at home and bouncing through short-term jobs.

The family often communicates with their off-world (and usually unseen) boss, the Big Giant Head (William Shatner). His orders are received through Harry, who unexpectedly (and often in inconvenient circumstances) stands up, his arms stiff (acting as the antenna), and proclaims: "Incoming message from the Big Giant Head."

Source: Wikipedia.