One way his credibility is established is by being an expert on the topic. Tyson is “An American astrophysicist and the director of the Hayden Planetarium at the American Museum of Natural History” (Tyson, 161). By being an expert on the topic it makes him easier to trust and listen to, since he knows what he is talking about. Also, by mentioning other scientists such as, “The twentieth-century German physicist Max Planck” (Tyson, 166) it shows that another expert who is credible agrees with what he is saying. By showing credibility it makes readers listen and retain the information more since it is said by