Tag Archives: Time

Why do we say A.M. and P.M. when telling time?

The  letters A.M (ante meridian) P.M (post meridian) tell us  what part of the day it is on a 12 hour clock. As we all know, there are 24 hours in a day but only 12 hour numbers on a clock.   This is because in  most  countries the hours of the day are usually divided …

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What is a light-year?

Space is so vast that astronomers don’t use miles to measure how far stars are away from us.  The numbers of miles would be so large that you would have a difficult time using them. Instead, astronomers use what they call “light-years” to measure great distances.  A light-year is the number of miles that light …

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How does a sundial tell time?

Long before we had clocks and watches, people used sundial to tell time.  A sundial is really a shadow clock – it tells the time by the sun’s shadow. A sundial consists of the dial face and the gnomon (pointer), which is set in the center of the dial.  The dial is divided into hours. …

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Why do we have time zones?

Time zones establish a regular sequence of time changes around the world.  All the places in each zone have the same time.  It is called standard time.  Travelers often pass through time zones.  When it is noon in Chicago, for example, nit is 6 o’clock in the evening in London. We can understand why time …

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