Dictionary.com defines the adjective "solar" as "of or pertaining to the sun." A second and less utilized definition is "a private or upper chamber in a medieval English house."
The word "solar" derives from the Latin "sol," which means "sun." A common use of the word "solar" is in the term "solar system," a group of celestial bodies and planets that revolve around the sun or another star. "Solar" is also often used to designate energy obtained from the sun. The U.S. Department of Energy calls solar energy "the most abundant energy resource on earth," with more solar energy available at any time than the world's total energy use.
In remote and developing areas of the globe, people harness solar energy to power simple ovens. In developed countries, solar energy is used as a renewable alternative to fossil fuels. In space, solar energy fuels sophisticated satellites. As of April 2014, the Solar Impulse 2, a single-seat solar-powered plane, is expected to make the first solar flight around the world in 2015. By harnessing solar power, the plane is able to operate without stopping to refuel. The aircraft's flight around the globe is scheduled to take 5 continuous days and nights.