Sept. 19, 2012: An F-15E Strike Eagle receives fuel from a 100th Air Refueling Wing KC-135 Stratotanker during a training mission over the Atlantic Ocean. (© Ethan Morgan/U.S. Air Force via Reuters)
Drakens over Sweden. These jets look like they're from Battlestar Galactica.
An F/A-18 Hornet was photographed just as it broke the sound barrier. When an airplane travels at a speed faster than sound, density waves of sound emitted by the plane cannot precede the plane, and so accumulate in a cone behind the plane. When this shock wave passes, a listener hears all at once the sound emitted over a longer period: a sonic boom. As a plane accelerates to just break the sound barrier, however, an unusual cloud might form. The origin of this cloud is still debated.