Alan Alda presents a provocative science special with a Baltimore angle on Maryland Public Television, and Nick At Nite offers a blessed event in a memorable "Bewitched" repeat.
* "Scientific America Frontiers: Life's Big Questions" (8 p.m.-9 p.m., MPT, Channels 22, 67) -- The Baltimore-based operation of the Hubble Space Telescope gets some attention. Among those big questions: Who else might be out there? PBS
* "Beverly Hills, 90210" (8 p.m.-10 p.m., WBFF, Channel 45) -- A repeat of the season finale sets up some of the plot questions to be resolved soon in a new season, as the series' principals travel to Palm Springs for a convention. Fox.
* "Dateline NBC" (9 p.m.-10 p.m., WBAL, Channel 11) -- Last fall, two 17-year-old Native American youths, members of the Tlingit tribe of Alaska, were banished to separate islands by tribal elders for robbing a pizza deliveryman. Correspondent Jon Scott updates the story. NBC.
* "Nurses on the Line: The Crash of Flight 7" (9 p.m.-11 p.m., WJZ, Channel 13) -- Lindsay Wagner, former "Bionic Woman," by necessity becomes leader of a group of nursing students whose plane crashes in a Mexican jungle in a 1993 based-on-fact TV movie. CBS.
* "Mark Russell Comedy Special" (9 p.m.-9:30 p.m., MPT, Channels 22, 67) -- The peerless political punster says he has 535 writers for his latest outing: members of the Senate and House of Representatives. PBS.
* "The Taking of Pelham One Two Three" (8 p.m.-10:25 p.m., TNT) -- Thrillers just don't get much better than this 1974 film. Walter Matthau is a weary transit cop and Robert Shaw is the leader of a band of nasties who hijack a Manhattan subway train and threaten to kill a passenger every minute until their ransom is paid.
* "Bewitched" (8 p.m.-11 p.m., Nick At Nite) -- Trivia test: How many actresses played Tabitha, the bewitching baby born in this 1965 episode of the 1964-1971 series? Those identical twins of "Full House" were nothing new. Three sets of twins played Tabitha as she grew. Male twins played brother Adam, born in the 1970-1971 season. Nick airs a series of episodes tonight.
* "Dream On" (10 p.m.-10:30 p.m., HBO) -- The funny adult comedy reaches a rarefied plateau for original cable series: A 100th episode. Martin (Brian Benben) has a near-death experience that causes him to re-examine his life.