• workers tend to a well head during a hydraulic fracturing operation at an Encana Oil & Gas (USA) Inc. gas well outside Rifle, in western Colorado on March 29, 2013

    Companies that drill for oil and natural gas on federal lands will be required to disclose publicly the chemicals used in hydraulic fracturing operations.

    LAST UPDATE : May 16, 2013, 6:37 PM EDT
  • The Solar Impulse lands during a test flight at Moffett Field NASA Ames Research Center in Mountain View, Calif., Friday, April 19, 2013

    A solar-powered plane that has wowed aviation fans in Europe took to the skies over the San Francisco Bay area.

    LAST UPDATE : Apr 19, 2013, 5:05 PM EDT