Move over Spiderman, Batman and Superman. A new hero zooms across your television screen beginning today: "Captain Planet and the Planeteers" (TBS at 8:35 a.m. with an encore at 5:35 p.m.). With the help of Gaia, the spirit of earth, and his five planeteers, Captain Planet sets out to save the environment.

Using rings given to them by Gaia, the five young planeteers each control one special element of nature: earth, wind, water, fire and heart. Each week the eco-heroes take on eco-villains and avert an environmental disaster.

Dave Coburn ("thirtysomething") voices Capt. Planet; Whoopi Goldberg does Gaia. Big-name guest voices include Martin Sheen, Meg Ryan, Jeff Goldblum, Phyllis Diller and Ed Asner, who today voices "Hoggish Greedily," an oil rig operator who is jeopardizing the coastline.

The show has also been syndicated to 185 stations, including WDCA (Channel 20) at 9 a.m. on Sundays.

Another presentation of note on TBS Sunday is the "Roller Coaster!" segment of "National Geographic Explorer" at 9 p.m. In addition to a delightful look at the origin of roller coasters and some of yesteryear's pretzels, corkscrews and loops, this piece examines the fiendish Pipeline, twisting, turning and snaking through space, riding neither on top or below the tracks but rolling between them like an acrobatic plane. The coaster isn't due for public trial and thrill for two years, but designer Ron Toomer sees it as the prime attraction in amusement parks for a decade.

Sunday on Arts & Entertainment at 9 p.m., the premiere of "The Life of Agatha Christie" celebrates the 100th anniversary of her birth (Sept. 15). The one-hour show, co-produced with BBC, has an encore Thursday at 9 p.m. The week-long salute to Christie includes "Miss Marple: The Moving Finger," Monday at 9; "Murder by the Book," Tuesday at 9:30; "Partners in Crime: The Affair of the Pink Pearl," Thursday at 10, and "Miss Marple: A Caribbean Mystery," next Sunday at 9.

Sunday on The Discovery Channel at 10 p.m. "Discovery Sunday" takes a look at "The Lighthouse" and a obsolete way of life. On a tiny island off Wales, the lighthouse keeper -- and last inhabitant -- bids farewell. Encore: 2 a.m.

Sunday on Bravo at 5 p.m. "Grim Tales," with Rik Mayall telling Brothers Grimm stories, moves into the network's "Culture For Kids" hour.

Thursday on VH-1 at 7 p.m. "The Great TV News Stories" goes into its second week with "Racing for the Moon: America's Glory Days in Space." The series, acquired from ABC Distribution Company, highlights stories from the past three decades and features ABC news casters and anchors. Next week: "The Great Debates: John F. Kennedy vs. Richard M. Nixon."

Thursday on Bravo at 8 p.m. "The South Bank Show" boasts a rare profile of filmmaker Robert Altman, who recently said the reason he agreed to do this show was because of a "South Bank Show" with Francis Bacon. "It was wonderful," he noted. "He was drunk the whole time. And I thought, 'How can I pass up something like this?' "