Best of 2008: New stem cells, far-off planets
Breakthrough of the year:
Cellular reprogramming. Researchers, including a team led by Dr. George Q. Daley of the Harvard Stem Cell Institute and Children's Hospital Boston, produced made-to-order stem cells by reprogramming skin cells from ill patients. These cell lines - which, like embryonic stem cells, seem able to grow into any kind of tissue - and the techniques for producing them, offer long-sought tools for understanding, and possibly someday curing, hard-to-study diseases such as Parkinson's and type 1 diabetes.
Runner up: Seeing exoplanets. For the first time, astronomers directly observed planets orbiting other stars, using special telescope techniques to distinguish the planets' faint light from the stars' bright glare.
Cancer genes. Dozens of mutations that remove the brakes on cell division and send the cell down the path to cancer were found by sequencing genes from various cancer cells, including pancreatic cancer and glioblastoma, two of the deadliest cancers.
Mystery materials. A second family of high-temperature superconductors - materials that carry electricity without resistance at inexplicably high temperatures - was discovered, consisting of iron compounds instead of copper-and-oxygen compounds.
Watching proteins at work. Biochemists encountered major surprises as they watched proteins bind to their targets in cells, switch a cell's metabolic state, and contribute to a tissue's properties.
Renewable energy. Researchers found a promising tool for storing excess electricity generated from part-time sources like such as wind and solar power, on an industrial scale. A cobalt-phosphorus catalyst that's relatively easy to come by can use electricity to split water to free its hydrogen, which can in turn be fed into fuel cells to produce electricity again.
Embryo video. The dance of cells in a developing zebrafish embryo were observed in unprecedented detail as scientists made movies that traced the movements of the roughly 16,000 cells that form by the end of its first day of development.
Good fat. In a study that may offer new approaches to treating obesity, scientists discovered they could morph good brown fat, which burns bad white fat to generate heat for the body, into muscle and vice versa.
Calculating the weight of the world. Physicists now have the calculations in hand to show that the standard model - which describes most of the visible universe's particles and their interactions - accurately predicts how much mass protons and neutrons have.
Faster genome sequencing. Researchers reported a flurry of genome sequences this year - from woolly mammoths to cancer patients - aided by sequencing technologies that are quicker and cheaper than the ones used to sequence the first human genome. 