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.

"Biography," with host Iain Stewart, isn't exactly a tell-all, but it adopts an interesting alternative to focusing on each land mass in turn. Instead, the three-night series explores the natural forces that have given the Earth its winning personality.

Airing tomorrow, "Volcanoes" is followed by "Ice," which investigates a powerful force in carving the landscape and altering the Earth's climate.

On Monday, "Atmosphere" finds Stewart taking off into the stratosphere aboard one of the planet's swiftest aircraft.

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

Finally, Tuesday, "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.