Kevin Costner, Bette Midler, Ted Danson, Michael...

Kevin Costner, Bette Midler, Ted Danson, Michael Keaton, Meryl Streep, Robin Williams, Barbra Streisand and Bruce Willis are among the headliners who will appear in ABC’s “The Earth Day Special” on April 22. Through comedy, drama and music, the two-hour special will attempt to illustrate how the earth’s environment has reached a state of crisis and explore solutions to conserve the planet’s remaining resources.

Next fall, the teen musical group New Kids on the Block will star in a live-action/animation series for ABC. Each week, the half-hour show will open with the New Kids playing a song in concert and then whisk them away to Toon Town as “regular kids” who just happen to be rock stars.

CBS’ 9-year-old series “Falcon Crest” is undergoing a face lift. Next month the show will take on femme fatales Susan Blakely and Sheryl Lee Ralph as cast members. And Jane Wyman, who has starred as Angela Channing since the show’s premiere in 1981, will return for the final three episodes of the season.

Alexis Smith, who played Clayton Farlow’s diabolical sister Lady Jessica Montfort on “Dallas” during the 1983-84 season, will reprise her evil role on the CBS series in May. Smith’s character will return to the long-running serial from a sanitarium for the criminally insane where she was sent after a failed kidnap attempt of Miss Ellie (Barbara Bel Geddes).

Showtime cable will celebrate Britain’s most infamous comedy troupe with “Monty Python: 20 Odd Years,” two hourlong specials airing on March 16 and 17. The first special, “Life of Python,” will offer a behind-the-scenes look at the troupe’s members; the second, “Twenty Years of Monty Python (Parrot Sketch Not Included),” will present clips of favorite Python moments.