What is UTC or Zulu Time?
UTC (Coordinated Universal Time, Universal Time Coordinated, Universal Coordinated Time, Universal Time) is the standard time common to every place in the world. Formerly and still widely called GMT (Greenwich Mean Time) and also World Time, UTC nominally reflects the mean solar time along the Earth’s prime meridian. (The prime meridian is 0° longitude in the 360 lines of longitude on Earth. There are 179 meridians toward the East and 179 toward the West. The 180th meridian is also called the International Date Line.) The prime meridian is arbitrarily based on the meridian that runs through the Greenwich Observatory outside of London, where the present system originated. The UTC is based on an atomic clock to which adjustments of a second (called a leap second) are sometimes made to allow for variations in the solar cycle. Coordinated Universal Time is expressed using a 24-hour clock but can be converted into a 12-hour clock (AM and PM). UTC is used in plane and ship navigation, where
