URBANA, Ill. — Time through the ages has been adapted for many purposes. The Romans were known to change the calendar to keep a politician in office longer. Some calendars work off moon cycles, others don’t. Todd Gleason files this report on the Gregorian calendar and how it is used to tell time.
This is the official voice of time in the United States. It is the U.S. Naval Observatory Master Clock Announcer, a voice many radio & television stations depend upon.
The U.S. Naval Observatory’s written mission includes determining the positions and motions of the Earth, Sun, Moon, planets, stars and other celestial objects, providing astronomical data; determining precise time; measuring the Earth’s rotation; and maintaining the Master Clock for the United States.
The U.S. works off the Gregorian or Christian calendar and our concept of a year, time, is based on the earth’s motion around the sun. The time from one fixed point, such as a solstice or equinox, to the next is called a tropical year. Its length is about 365 days, but varies by a few minutes or hours.
Our concept of a month is based on the moon’s motion around the earth. Although, this connection has been broken in the calendar we now use. The time from one new moon to the next is about 29 and half days. So the moon cycles, and our monthly Christian calendar don’t quite coincide. It has years of 365 or 366 days, is divided into 12 months that have no real relationship to the motion of the moon and groups weeks in sets of seven days.
Today, a website called “Calendars Through the Ages” reports, almost everyone takes the precision of our calendars for granted, unaware of the long threads spooling out from our clocks and watches backward in time, running through virtually every major revolution in human science, all linked to the measurement of time. The thread, it says, runs largely through the West, since this is the source of the world’s civic calendar, but also casts lines of varying sizes and thickness outward to China, India, Egypt, Arabia, and Mesopotamia.
Unwinding backward, it pauses at Clavious and at Bacon; at the rush of knowledge coming from Islam and the East during the Middle Ages; at bloody wars fought over dates after Rome’s collapse; and at Rome at its height, when Julius Caesar fell in love with Cleopatra, an affair that gave the west its calendar.
It moves back farther still to the Egypt of the pharaohs, Babylon, and beyond, thousands of years before our own calendar was created. Many different calendars have been developed over the millennia to help people organize their lives. According to a recent estimate, there are about forty calendars used in the world today, particularly for determining religious dates. Most modern countries use the Gregorian or Christian calendar for their official activities.
Music: under and out
Nat Sound: USNO Master Clock Voice Announcer
Time Service Department U.S. Naval Observatory
USNO Master Clock Voice Announcer
[www.time.gov](www.time.gov)
— Todd Gleason, Farm Broadcaster
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