light hour - the distance light travels in a vacuum in one hour; approximately one billion kilometers. 1  astronomy unit - a linear unit used for astronomical distances. 2  light year, light-year - the distance that light travels in a vacuum in 1 year; 5.88 trillion miles or 9.46 trillion kilometers.
keystone. n. 1. (Building) Also called: headstone or quoin the central stone at the top of an arch or the top stone of a dome or vault.2. something that is necessary to connect or support a number of other related things.(ËkiËstoÊn). n.eystone. n. 1. (Building) Also called: headstone or quoin the central stone at the top of an arch or the top stone of a dome or vault.
Keystone is a census-designated place (CDP) in Summit County, Colorado, United States. The population was 1,079 at the 2010 census. The Dillon Post Office (ZIP Code 80435) serves Keystone postal addresses. Keystone is the home of the Keystone Resort. Originally constructed in the 1970s by the Ralston Purina Company, it is now owned by Vail Resorts. The Keystone Resort ski area occupies 3 separate mountains: Dercum Mountain, North Peak, and The Outback.