'Cosmos' Episode 7 Preview: Neil DeGrasse Tyson Discovers Earth's Age In 'The Clean Room' [VIDEO]

"Cosmos" returns to Fox on Sunday night with a new episode. In "The Clean Room," Neil Degrasse Tyson explores Earth's age and the work of geochemist Clair Patterson, voiced by Richard Gere.

According to the Fox synopsis, "'To determine the true age of the Earth, geochemist Clair Patterson (guest voice Richard Gere) developed the uranium-lead dating method to make an unprecedented discovery – calculating Earth's age of 4.5 billion years. But Patterson's groundbreaking discoveries were just beginning. Patterson made it his mission to draw public attention to the detrimental effects of lead in the environment and dedicated his career to fighting against the petroleum and chemical industry, eventually achieving public health's biggest victory of the 20th century."

In the first "Cosmos" clip, "Cold Storage Between Jupiter and Mars," Tyson travels to the asteroid belt between Mars and Jupiter. As NASA explains, the asteroids found in the main belt are what is left over from the formation of the solar system approximately 4.6 billion years ago.

The next two "Cosmos" previews focus on Clair Patterson, the geochemist who accurately determined the Earth's age as well as the dangers of lead pollution. According to Patterson's New York Times obituary from 1995, he determined the Earth's age in a study published in 1953 using a technique known as radioactive dating, or radiometric dating, based on the decay rate of radioactive elements such as uranium. Over time, uranium decays into lead and Patterson was able to determine the age of meteorite that crashed into the Earth and concluded the Earth was 4.6 billion years old.

Patterson's work with lead also determine the increased levels of the element in the environment. As a result of his research, lead in petroleum was phased out in the Clean Air Act of 1970. The title of the "Cosmos" episode is a nod to Patterson working in a "clean" room after discovering lead contamination in research laboratories.

The latest episode of "Cosmos" airs on Sunday at 9 p.m. EDT on Fox and on National Geographic, Monday at 10 p.m. EDT.