More ominous signs Wednesday have scientists saying that a global warming "tipping point" in the Arctic is happening before their eyes: Sea ice in the Arctic Ocean has melted to its second lowest level since satellite observations began.

The plucky Mars rover Opportunity is driving out of the giant Victoria Crater nearly a year after a dangerous descent to examine exposed bedrock.

NASA said engineers noticed a power surge in Opportunity's left front wheel and decided to pull it out of the crater before it got stuck. Its twin rover, Spirit, lost function in its right front wheel in 2006 after a similar surge, but can still drive on flat terrain.

Two wind power developers plan to buy 585 megawatts of transmission capacity on a new power line to be built in eastern Wyoming - a prospect that could more than double the state's wind energy output, state and industry representatives said Tuesday.

If you've ever found yourself in your local supermarket agonizing about whether the organic apples will be a more nutritional and greener choice than the cheaper non-organic ones, you're probably not alone.

Two teenage girls used DNA bar coding to determine that some sushi on New York dinner plates was mislabeled with cheaper fish being passed off as a more expensive species.

Some of the gullies that cut the sides of Martian craters were likely formed by meltwater from glaciers that existed a few million years ago, when Mars was wetter than it is now, a new study suggests.

"Beware: exploding lungs" is not a sign one would expect to see at a wind farm. But a new study suggests this is the main reason bats die in large numbers around wind turbines.

Have you ever noticed that herds of grazing animals all face the same way? Images from Google Earth have confirmed that cattle tend to align their bodies in a north-south direction.