The difference between a.m. and p.m. is in the time of day. The designation a.m. refers to any time that is after midnight and prior to noon. Any time that is between noon and midnight is designated p.m.Know More
The designation a.m., which is short for ante meridiem in Latin, means "before the sun passes the meridian." An example of a.m. usage is 10:00 a.m. The designation p.m. is short for post meridiem in Latin. An example of p.m. usage is 3:00 p.m. Noon refers to 12:00 p.m., and midnight refers to 12:00 a.m.
The U.S. Army uses a 24-hour format to indicate time rather than a 12-hour format, so a.m. and p.m. are not needed.Learn more about Time & Calendars
One year is measured by the time it takes a planet to orbit the sun, and 365 days is the best estimate for how long it takes Earth to complete a full trip around the sun. Years on other planets are measured in comparison with the Earth year, and one year on most planets is longer than one year on Earth.Full Answer >
The 24-hour clock was developed in ancient Egypt and was based upon careful astronomical observations and shadow clocks similar to the modern garden's sundial. Originally the length of these hours varied from season to season due to differing lengths of daylight.Full Answer >
At the time of this writing, the year is 2014 on the internationally popular Gregorian calendar. On the Gregorian calendar, years are numbered in the present common era (C.E., also known as Anno Domini, or A.D.) from the birth of Jesus Christ, according to the Christian religion.Full Answer >
Calculating time as a fraction of an hour is often necessary for filling out time cards, billing clients and completing spreadsheets. Using fractions instead of counting minutes creates a smoother process and totals the time as hourly segments.Full Answer >