Today on TV

Nova (7 p.m., Ch. 7): "AstroSpies" looks at plans both Americans and Soviets had to build manned satellites to spy on one another.

American Idol (7 p.m., Ch. 13): In this two-hour episode tonight and the one-hour episode on Wednesday, the field of 164 hopefuls who made it to Hollywood will be trimmed to 24.

High school basketball (7 p.m., Ch. 14): Cottonwood at Highland

Big Brother (8 p.m., Ch. 2): This tacky show is tackier than ever as it begins its ninth season. The 16 contestants are each assigned partners of the opposite sex, and they share everything — including a bed.

The Mormons (8 p.m., Ch. 7): The conclusion of last year's two-part, four-hour documentary is repeated.

One Tree Hill (8 p.m., Ch. 30): The nanny is after Nathan.

Jericho (9 p.m., Ch. 2): The second-season premiere starts off with a bang — literally — as the new government based in Cheyenne, Wyo., steps between the battling towns of Jericho and New Bern. It's a rousing start to a very promising, seven-episode season that should satisfy the fans who talked CBS into uncanceling this show.

Boston Legal (9 p.m., Ch. 4): Scott Bakula, who starred opposite Candice Bergen in 13 episodes of "Murphy Brown" in the mid-1990s, appears opposite her in court in this episode. Bakula was also a captain of the starship Enterprise (on "Star Trek: Enterprise"), as was "Boston Legal" star William Shatner (on the original "Star Trek" series). If Bakula and Shatner have any scenes together, won't it mess up the space-time continuum or something?