ONE SMALL STEP: APOLLO 13: People who know their moon missions -- and even people who don't, but who might have seen something like the Tom Hanks-starrer "Apollo 13" -- know about the aborted space trip made on April 11, 1970. Griffith Observatory looks back at the heroes of Apollo 13, and what happened, over several nights this week. Tonight is "Houston, We Have a Problem." 7:30 p.m.
"AMERICA'S FUNNIEST HOME VIDEOS 20TH ANNIVERSARY": This "send in your VHS tapes" show documenting all sorts of pratfalls and hijinks came way ahead -- way way way ahead -- of the online videos and the reality television phenomenon. Tom Bergeron and behind-the-scenes people will be on the panel. If you're a member of the Paley Center for Media, you can attend for free. 7 p.m.