Neil deGrasse Tyson explores the deepest parts of the Earth's past in the latest episode of Cosmos: A Spacetime Odyssey entitled "The Clean Room." In the new episode, Tyson investigated the real age of the Earth using current dating methods.

The new episode of Cosmos was aired by Fox last Sunday. Tyson delved into an investigation regarding the age of the planet while reviewing the work of Clair Patterson, a geochemist who was also an expert on dating methods that use uranium and lead.

"'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," says Fox in a synopsis of the episode. "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."

Patterson is best known for calculating what is considered to be the most accurate estimate of the real age of the planet. Patterson developed a dating method that he used to come up with his estimate. By assuming that meteorites are lumps of rocks that were created during the birth of the Solar System, Patterson believed that accurately measuring the age of meteorites could also lead to the age of the Earth. After studying various specimens of space rocks, he determined that the Earth is 4.550 billion years old with a margin of error of around 20 million years. In the latest Cosmos episode, Patterson was voiced by Richard Gear.

The episode's title may be a reference to the fact that Patterson helped bring about the phasing out of lead in petroleum back in the 70s. His work with lead helped people realize that the amount of lead in the environment was increasing. His findings were part of the reason for the passing of the Clean Air Act of 1970.

The content of the new episode may also bring about another clash with some creationist supporters who believe that the Earth is only a few thousand years old based on Biblical sources. Creationist scientists and believers have already called out the show for being "biased" in the past. The first episode of the show involved an incident where a 14 second segment discussing evolution was cut off during the show's airing in Oklahoma. In Cosmos episode "Sky Full of Ghosts," Tyson also debunked the creationist theory that the Earth is only 6,500 years old using the distance between the Earth and the Crab Nebula.