Sunday night's Cosmos premier ended with a touching personal story from Neil deGrasse Tyson on how he first met astrophysicist and science communicator Carl Sagan.

Sagan, who died in 1996, was an astronomer, astrophysicist and an avid and skilled science communicator. He hosted the original PBS series Cosmos: A Personal Voyage. He also taught at Cornell University, wrote the book Contact and many others, and published more than 600 scientific papers.

At the end of the episode, deGrasse Tyson whips out Sagan's personal journal. On December 20, 1975 the entry says "Neil Tyson." At the time deGrasse Tyson was just a 17-year-old kid from the Bronx with dreams of being a scientist, but Sagan had invited him to spend a Saturday with him in Ithaca at Cornell University, after seeing his application to attend University there.

He toured their labs there, and Sagan gave him a book, "The Cosmic Connection" and inscribed it "to a future astronomer": DeGrasse Tyson describes how this influenced his entire life:

At the end of the day, he drove me back to the bus station. The snow was falling harder. He wrote his phone number, his home phone number, on a scrap of paper. And he said, "If the bus can't get through, call me. Spend the night at my home, with my family."

I already knew I wanted to become a scientist, but that afternoon I learned from Carl the kind of person I wanted to become. He reached out to me and to countless others. Inspiring so many of us to study, teach, and do science. Science is a cooperative enterprise, spanning the generations.

Here's him describing the meeting on a talk show. Tyson eventually went to Harvard for his undergrad, but he says: "To this day I have this duty to respond to students who are inquiring about the universe as a career path to respond to them in the way that Carl Sagan had responded to me."