Love it or hate it, the biggest show on the planet - American Idol - is back and rarin' to go with a new judge (meet Kara DioGuardi) and some new twists (the semifinal round will consist of 36 singers, not 24). The changes come after Idol showed signs of waning popularity in Season 7. Still, the musical juggernaut is once again expected to crush everything in its path. And, as usual, it kicks off with the audition rounds, which too often prove to be an assault on both the ears and eyes. Brace yourself. (8 p.m., WBFF-Channel 45)
Cashing in: Remember that stuff you probably had more of a year ago than you do today? Take a sentimental journey with The Ascent of Money, a two-hour documentary that traces the evolution of money through human history, and helps account for why money is the fulcrum of civilization. The film is written and presented by author, economist, historian and Harvard professor Niall Ferguson, based on his new book of the same title. (9 p.m., MPT-Channel 22)
Grisly baggage: On a new episode of Homeland Security U.S.A., a motorist is bewildered when border cops express concern over the human skull and handguns found in his possession. What, those aren't standard features in vehicles nowadays? (8 p.m., WMAR-Channel 2)
Late-night guests: Actor Mickey Rourke visits The Tonight Show with Jay Leno , and actress Salma Hayek stops by Late Show with David Letterman.
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David Zurawik is on assignment. His column does not appear today.