83-Why India is unusual having a single time zone? India, for such a large country, spanning over 30° of longitude, is unusual in having a single time zone all over the country, 51/2 hours fast. (Ideally, India should have two time zones.) The standard time in India is the local time of a place at 82.5°E longitude near Allahabad. This meridian also divides India approximately into half. INTERNATIONAL DATE LINE 84-When and who designed the International Date Line? Why it was adopted? The 180th meridian was designated the International Date Line by the Intemational Meridian Conference in 1884. It was adopted in order to avoid the confusion of the difference of one day that travellers would face while travelling across the globe. Counting from Greenwich Meridian, the date immediately east of this line is one day ahead or 12 hours faster than in the west. Though the 180° meridian generally falls over the ocean, the International Date Line has had to deviate both eastward and westward in order to permit certain landmasses and islands to have the same calendar day. It passes through the Arctic Ocean, Chukchi Sea, avoids Wrangel Island and Russian landmass, passes through Bering Strait, veers again to avoid Aleutian Islands, and goes through Pacific Ocean. A few degrees south of the equator the date line has shifted 71/2° eastward, avoiding Fiji and Tonga island groups which have the same days as New Zealand. CALENDAR 85-How does one year time complete? The time taken for the earth to complete one orbit of the sun is called a year. It is measured in a number of ways-sidereal year, measured with respect to fixed stars; solar year, time taken by sun to make two successive appearances at the point of Aries; and the calendar year which is regulated using leap years so that it is equal to that of the solar year (365.2419 mean solar days), To the usual year of 365 days, one day is added in the month of February every fourth year, making it a leap year. This correction, being too large, 86-When the leap year is omitted? The leap year is omitted in the century years (1800, 1900, etc.) unless the year is divisible by 400. Thus, the year 2000 was a leap year. 87-How the period time of year is divided into different units? The year is divided into months, originally calculated by the revolution of the moon around the earth. But the lunar month of about 29'th days has now been made slightly longer, whereby the months and seasons occur at the same time every year. Months are further divided into weeks, which are arbitrary divisions made by man, each unit having seven days. 88-In the ancient past which system was used to measure time? In the ancient past, too, man had devised systems of measuring time. The earliest Roman calendar based on agricultural months is an example. 89-Who corrected the drawback in the Raman calendar? What were the new advancements he made in it? This, however, had drawbacks and was corrected by. Julius Ceasar by adding 90 days to 46 BC and declaring each year thereafter to be 365 days, every fourth year being a leap year. But this meant a loss of about three-quarters of a day (18 hours) in a century. 90-Who gave the final touch to calendar? It was Pope Gregory XIII who gave the final touch to the calendar, which has now been universally adopted, by decreeing that the last year of a century would be a leap year only if it were divisible by 400. Though near perfect, the Gregorian calendar is not uniformly divisible into quarters of months, neither are the months divisible into equal number of days. 91-Who had lunar calendars? The Babylonians, Sumerians and ancient Egyptians had lunar calendars. SOLAR TIME 92-What are the two different ways to determine the Solar time? Solar Time, or sun time, is determined in two ways. Apparent Solar Time and Mean Solar Time.
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