The Clean Sky Joint Undertaking (CSJU) is a public-private partnership between the European Commission and the European aeronautics industry that coordinates and funds research activities to deliver ...
When they look at sky brightness—what they call the sky background—they use a unit of brightness per area of the sky: how much light is spread out over a given parcel of celestial real estate.
Want to rid your walls of pesky marks and buildup? Learn how to clean walls simply and safely with these expert cleaning tips. If you haven’t been washing your walls, you’re not alone.