HIGHLIGHTS FOR TV NEXDT WEEK

Last year, Discovery Channel presented "Planet Earth," which was billed as the ultimate portrait of our planet.

Not to be eclipsed, National Geographic Channel is unveiling "Earth: The Biography," which, two years (or several billion years?) in the making, visits all seven continents, capturing a world of beauty in high definition.

With five hours airing over three nights, this "Biography" isn't exactly a tell-all, but it adopts an interesting alternative to focusing on each land mass in turn. Instead, the series explores the natural forces that have given the Earth its winning personality.

Host Iain Stewart rappels close enough to feel the heat from the lava lake of Ethiopia's Erta Ale volcano, then reminds us that this is more than a magnificent sight: "It's a window that allows us to look deep into the Earth."

Airing Sunday at 9 p.m. "Volcanoes" is followed at 10 p.m. by "Ice," which investigates a powerful force in carving the landscape and altering the Earth's climate, but, as Stewart shows us in Greenland, is also melting at a phenomenal rate.

Monday at 9 p.m. "Atmosphere" finds Stewart taking off into the stratosphere aboard one of the planet's swiftest aircraft. Then we witness some of the most violent lightning on Earth and, in Arizona, behold a rock formation sculpted by the wind.

At 10 p.m. , "Oceans" dives into the watery realm that sets the Earth apart from every other planet in the solar system.

Finally, Tuesday at 10 p.m., "Rare Planet" examines the forces beyond the planet that created Earth and still protect it, while taking a new look at a force that could imperil it: humankind.

Other shows to look out for:

- As Mandy Gilbert nears her 18th birthday, two things are high on her wish list: a cool new cell phone and Drew Patterson, the hottest guy in the senior class. Mandy gets her phone. Drew invites her to an all-important party. But then she's grounded. Can she sidestep her loving but overprotective dad as well as Lisa, Drew's perfectly smug ex-girlfriend? Or is the party over for Mandy before it started? Ashley Tisdale ("High School Musical") is back in school for the ABC Family film "Picture This!" Kevin Pollak co-stars as her father. It airs Sunday at 8 p.m.

- A week of new episodes of "Avatar: The Last Airbender" culminates with a two-hour finale on Nickelodeon. A cartoon series in the anime style, "Avatar" centers on Aang, a fun-loving 12-year-old who must forgo a normal life to lead the fight against the hostile Fire Nation. The conclusion of Book Three rolls out nightly at 8 p.m. starting Monday, with an hour-long installment Wednesday. Then Saturday, four back-to-back half-hours (titled "Sozin's Comet") wrap up the saga.

- Emeril Lagasse's gone green! The renowned chef is starring in a new series, "Emeril Green," on the new Planet Green cable channel. On each episode, Lagasse assists cooking-impaired individuals in selecting the best foods, then preparing them for a wholesome meal. For example, he helps ballroom dancer Marnie prepare a meal from several different types of fish. On another edition, he offers some pointers to Valerie, who loves steak but doesn't know which cut to buy, much less how to cook it. Kicking off Monday with six half-hours from 8 p.m. to 11 p.m. EDT, "Emeril Green" continues Tuesday through Thursday in its regular time slot, 8 p.m. to 9 p.m.

- "Reality Bites Back" is a reality show. No, "Reality Bites Back" is a satire. You're both right! Comedy Central presents its first unscripted competition series, with 10 comedians vying for supremacy in parodies of some of TV's most popular reality shows. Among the spoofed are "American Idol," "Survivor," "The Amazing Race," "The Biggest Loser" and "So You Think You Can Dance" (re-imagined here as "So You Think You Can Dive," with contenders getting 24 hours to become Olympics-worthy champs). Premiering Thursday at 10:30 p.m. with Michael Ian Black as host, "Reality Bites Back" airs after the revival of "The Gong Show," which features offbeat acts evaluated by celebrity judges. Premiering at 10 p.m.,"The Gong Show" is hosted by Dave Attell.