Comet Hyakutake; Chazz Palminteri; Substance Abuse Study; George Carlin

Dr. Neil deGrasse Tyson, professor Joe Patterson, and science writer Michael Lemonick explain what comets are and why newly discovered Comet Hyakutake is so important. Actor Chazz Palminteri talks about his latest film, "Diabolique." Joseph A. Califano, Jr. of the Center for Addiction and Substance Abuse, NYC Health Commissioner Margaret Hamburg, and Brooklyn D.A. Charles Hynes discuss the impact of substance abuse on all aspects of urban life. Comedian George Carlin talks about his career and upcoming stand-up comedy special, which will be his ninth special on HBO.