Neil deGrasse Tyson, astrophysicist, public intellectual and host of the "Cosmos" television series, will embark on a national speaking tour with the first dates set for January, the tour producer announced Monday. Tyson's Chicago stop, Jan. 27 at the Auditorium Theatre, is the second scheduled so far. Also announced are dates in Madison, Wisc., Denver, Los Angeles, San Francisco and Washington, D.C., with more cities to come, according to the producer, Innovation Arts & Entertainment of Chicago. Tickets for the shows, billed as "an evening of engaging conversation on science, exploration and the world as we know it," go on sale Friday; those for the Chicago event will cost between $55 and $92, said an event spokesman. Tyson is director of New York City's Hayden Planetarium.