TODAY'S MUST-SEE

Presidential debate and follow-up, 3 p.m., ABC, CBS, NBC, Fox, PBS, CNN, Fox News, MSNBC, C-SPAN and other cable news stations. Here's the third of the four debates, the second with presidential candidates John McCain and Barack Obama. Tom Brokaw is the moderator, but the audience has the power. It's a town-hall format.

TONIGHT'S MIGHT-SEE

"Nova: Arctic Dinosaurs," 8 p.m., PBS. The bones sat on a government shelf for years. A scientist had died in a rock fall before he could send them to the lab. Eventually, people realized what they had — 65-million-year-old dinosaur fossils from northern Alaska. Experts had thought that was impossible. This hour follows scientists who bore a 60-foot tunnel in the permafrost. It also offers fresh ideas about the end of the dinosaurs.

OF NOTE

"The Graduate" (1967), 2 p.m., TCM; "E.T." (1983), 3:15 p.m., HBO; "Bonnie and Clyde" (1967), 4 p.m., TCM. Here are three of the best-made films in movie history.

"Sanctuary," 4 p.m., Sci Fi Channel. Here's a second chance to see the pilot film before the show settles into its Friday slot. It starts as a so-so crime show, then gets much better in the second hour.

"The Real Housewives of Atlanta" debut, 6 p.m., Bravo. Atlanta, the people here say, is a vibrant place for wealthy blacks. This appealing reality show focuses on them, plus one white friend.

"Dancing With the Stars," 7 p.m., ABC. The results show airs an hour earlier than usual.

"Biggest Loser: Families," 7 p.m., NBC. The two-hour show is chopped in half; the second hour airs at 8 p.m. tomorrow.

"House," 7 p.m., Fox. Dr. House is supposed to help a teen who had a heart attack. He's distracted, however, by his dispute with Taub.

"The Shield," 7 p.m., FX. Here's one of the show's best episodes. It has great moments between Vic and his wife, a terrific twist involving Shane and superb work by Scott Michael Campbell as a naked suspect.