Best Bets on TV tonight

“Earth Days” (9 p.m., PBS): “Earth Days,” the latest installment of “American Experience,” traces the origins of the modern environmental movement, including the first Earth Day in 1970. Among those interviewed: former Secretary of the Interior Stewart Udall and Earth Day organizer Denis Hayes.

“Romantically Challenged” (9:32 P.M., ABC): Another TV vet, Alyssa Milano, returns to prime time in “Romantically Challenged.” She plays a recently divorced lawyer and mom who re-enters the dating scene. Just one problem: She hasn’t dated since Clinton was in office.

TV listings, B6