Calender
(a.k. hussain)
Calendar is a system of measuring and recording the passage of time. A major scientific advance was made when people realized that nature furnishes a regular sequence of seasons. The seasons governed their lives, determined their needs, and controlled the supply of their natural foods. They needed a Calendar so they could prepare for winter before it came.
Before the invention of the clock, people had to rely on nature''s timekeepers--the sun, the moon, and the stars. The daily apparent rotation of the sun provided the simplest and most obvious unit, the solar day. The seasons roughly indicated the length of another simple unit, the solar year. Early people were not aware of the fundamental cause of the seasons, the earth''s revolution around the sun. But it was easy to see the changing position and shape of the moon. As a result, most ancient calendars used the interval between successive full moons, the lunar month, as an intermediate measure of time. The month bridged the gap between the solar day and the solar year.
The lunar month, we now know, is about 291/2 days long. Twelve such months amount to about 354 days. This interval is almost 11 days shorter than the true solar year which has 365 days, 5 hours, 48 minutes, and 46 seconds. But a year of 13 lunar months would amount to about 3831/2 days, and would be more than 181/2 days longer than the solar year. The 13-month calendar is even less suited than the 12-month calendar to measure the year. This discrepancy explains the confusion that has existed in the calendar for thousands of years. People have no accurate way to keep both the lunar and solar calendars exactly in step.Write your abstract here.
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