Large changes in the sun's energy output may drive fluctuations in Earth's outer atmosphere.

Turbines on the Cedar Creek wind farm are silhouetted against a dramatic sunset. Completed in 2007, the Cedar Creek wind farm east of Grover, Colo., includes more than 250 turbines and generates roughly 300 megawatts of energy.

In a landmark test flight, the National Center for Atmospheric Research (NCAR) in Boulder, Colo., and a team of research partners this month successfully launched a solar telescope to an altitude of 120,000 feet, borne by a balloon larger than a Boeing 747 jumbo jet.

Carbon dioxide emissions from the burning of fossil fuels will produce a 3 percent reduction in the density of Earth's outermost atmosphere by 2017

By Laursen, Krista K; Jorgensen, David P; Brasseur, Guy P; Ustin, Susan L; Huning, James R A recently developed research aircraft will usher in a new era of environmental research opportunities for investigators wanting to study the Earth's atmosphere and surface on a worldwide basis.