Neil Degrasse Tyson is an American astrophysicist, have you heard of him? 
I have never heard of him
Oh he is really cool, Since 1996, he has been the Frederick P. Rose Director of the Hayden Planetarium. He also hosted Cosmos.
what exactly is an astrophysicist
They are those that have a degree in astronomy. For example,Neil Degrasse Tyson received a master's degree in astronomy
Oh, ok, what is the Hayden Planetarium?
Planetarium
A planetarium (plural "planetaria" or "planetariums") is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation.
A dominant feature of most planetaria is the large dome-shaped projection screen onto which scenes of stars, planets, and other celestial objects can be made to appear and move realistically to simulate the complex 'motions of the heavens'. The celestial scenes can be created using a wide variety of technologies, for example
Neil deGrasse Tyson
Neil deGrasse Tyson (; born October 5, 1958) is an American astrophysicist, author, and science communicator. Since 1996, he has been the Frederick P. Rose Director of the Hayden Planetarium at the Rose Center for Earth and Space in New York City. The center is part of the American Museum of Natural History, where Tyson founded the Department of Astrophysics in 1997 and has been a research associate in the department since 2003.
Tyson studied at Harvard University, the University of Texas at Austin,