The good news is that the ozone hole over Antarctica is slowly healing, thanks to controls on ozone-depleting substances that were once widely used in products such as refrigerators and aerosol cans. Stratospheric ozone protects us from harmful ultraviolet radiation that can cause problems such as skin cancer and crop damage.

By the time Lieutenant Colonel Michael Brill touched down after a combat mission over Iraq earlier today, he had broken his own world record for the most hours spent flying the F-16 Fighting Falcon. Brill, a 421st Expeditionary Fighter Squadron pilot, has logged more than 6,000 hours in the F-16.

An international team of scientists today published the first analysis of the genome sequence of Glennie, a female duck-billed platypus from Australia. Because the platypus occupies a unique branch on the tree of life, Glennie's genome could provide important clues about how humans and other mammalian species evolved.

Like all mammals, the platypus nourishes its young with milk. But platypus babies hatch from eggs, a characteristic usually associated with birds and reptiles.

By comparing the platypus genome with the genomes of other animals—including the human, mouse, dog, chicken and green anole lizard—the scientists hope to pinpoint which genes are common to all mammals, and when various traits have appeared or disappeared in the mammalian lineage.

The three members of the 16th International Space Station crew experienced a "ballistic trajectory" while returning from the station to the steppes of Kazakhstan in their Soyuz capsule on Saturday. Translation: Their spacecraft fell to earth like a lead weight, subjecting them to double the g-forces expected.

A metal that reacts with seawater to produce an electric field may help keep sharks at bay. But the idea isn't to protect humans from shark attacks. Just the opposite: scientists hope the metal will save sharks from senseless deaths in fishing nets.

An estimated 11 million to 13 million sharks die each year as "bycatch," collateral damage in the hunt for other fish. Sharks grow slowly and can take many years to reach reproductive age, so their populations are being severely impacted by fishing.

It's official: polar bears are in trouble. Secretary of the Interior Dirk Kempthorne has announced that he is accepting the recommendation of the U.S. Fish and Wildlife Service to list the polar bear as a "threatened" species under the Endangered Species Act. That means the bear is just one step from becoming "endangered," a category reserved for species on the brink of extinction.