US Naval Observatory info on Phenomena of the Sun and Moon, Time, Calendars and Historical Events, Computing Astronomical Data and Phenomena, Celestial Navigation, and more

USNO strengthens national security and critical infrastructure by serving as DoD's authoritative source for the positions and motion of celestial bodies, motions of the Earth, and precise time. USNO provides tailored products, performs relevant research, develops leading edge technologies and instrumentation, and operates state of the art systems in support of the U.S. Navy, DoD, Federal Agencies, international partners, and the general public. Astronomical data calculators (e.g., rise/set times, Moon phase, etc.), information on astronomical phenomena and related topics, astronomical and navigational almanacs, software products.