Everyone uses the conditions A.M and P.M to indicate before noon and afternoon. But do you know exactly what they mean and how these expressions came to expression?
As you know, the Earth's turn makes the sun and the stars seem to be moving across the sky. Of course, the daylight begins when the sun rises in the east and ends when it is in the west. When the sun is high in the sky, half of the daylight has been used between these two positions. Therefore, he knew that the sun was in the sky, which he could tell about the time of day. At night, star movement served the same purpose.
The important thing about keeping time is to know the exact moment of noon. For each of us is anywhere noon when the sun is directly overhead. Think of an imaginary line, a meridian, drawn across the sky, extending from the north side of your horizon down to the southern point. When the sun crosses your meridian, it is dinner for you. While the sun is still in the east of this line or meridian, it is morning. After the sun has crossed this meridian, it is afternoon.
The Latin word for "dinner" is the meridian, from which comes our word meridian. So A.M is an abbreviation for ante meridian or before noon. And P.M is the abbreviation for post meridiem or afternoon.
Each of the world's time zones is fifteen degrees wide to longitude, which is the distance the sun travels through the sky in an hour. Everyone living in the same time zone observes dinner at the same time. In this way, the time varies by one hour as you move through each time zone.
As you know, the Earth's turn makes the sun and the stars seem to be moving across the sky. Of course, the daylight begins when the sun rises in the east and ends when it is in the west. When the sun is high in the sky, half of the daylight has been used between these two positions. Therefore, he knew that the sun was in the sky, which he could tell about the time of day. At night, star movement served the same purpose.
The Latin word for "dinner" is the meridian, from which comes our word meridian. So A.M is an abbreviation for ante meridian or before noon. And P.M is the abbreviation for post meridiem or afternoon.
Each of the world's time zones is fifteen degrees wide to longitude, which is the distance the sun travels through the sky in an hour. Everyone living in the same time zone observes dinner at the same time. In this way, the time varies by one hour as you move through each time zone.
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