Year in science: Dig into DNA, out-of-this-world discoveries

— -- Distant worlds envisioned. Cellular secrets revealed. The subatomic world cracked open. Science hinted at a tantalizing future in 2008 with pictures of planets circling nearby stars, skin cells remade into embryonic tissues and the inauguration of the world's largest science experiment in Europe. "It was a good year for science," says news editor Robert Coontz of Science magazine. Take a look back at the stars of the Year in Science.

Flying through Saturn's moon's plume

NASA probes added to a legacy of daring space flybys, passing fairly close to Mercury and Saturn's mystery moon, Enceladus, including a 14-mile-high skim through a geyser plume. A lively scientific debate has erupted along with those plumes between scientists who suggest a lake lies hidden under the ice crust of Enceladus and those who disagree. Of all the discoveries at Saturn made by the Cassini spacecraft, a collaboration with the European Space Agency, "none has been more thrilling or carries greater implications" than the water jets blasting out of the south pole of Enceladus, said imaging team leader Carolyn Porco of the Space Science Institute in Boulder, Colo., at a recent science meeting.

In October, NASA's MESSENGER spacecraft sped just 124 miles above the Mercury, mapping never-before-seen territory on the solar system's innermost planet. The flight revealed 30% of Mercury previously hidden from view, a land area equal to the size of South America, and showed that the crust of the planet is a mishmash of materials, with ancient impact craters mixed with lava flows on the surface.

Findings about stem cells multiply

A crescendo of discoveries pushed stem cells from the lab dish to news headlines this year. Only two years ago, a Japanese research team led by Shinya Yamanaka of Kyoto University announced a method for turning mouse skin cells into unspecialized ones that resembled embryonic stem cells, prized by biomedical researchers for the potential to turn into any kind of tissue. This year, teams made use of the discovery in human cells to earn "Breakthrough of the Year" status from Science magazine.