Astrology : Time
The length of an astronomical year is 365.25 days or 365 days, 5 hours, 48 minutes, 45.2 seconds. Commonly a year has 365 days and therefore it is necessary once in four years to add a day to the year called leap year having 366 days. The rotation of Earth on its axis takes around 23 Hours and 56 Minutes.
1. GREENWICH MEAN TIME OR UNIVERSAL TIME
A mean solar day is equal to 24 hours. The mean solar time on the prime meridian is chosen to be the Greenwich Mean Time (GMT) or the Universal time. Noon at 12.00 Hours GMT occurs when the Sun crosses the Greenwich meridian. Almost all countries of the World follow the time which is + or – of GMT.
2 LOCAL MEAN TIME
The duration of a mean solar day is 24 hours. Whenever the Sun crosses the meridian circle of a particular place, it is local noon for that place.
3. STANDARD TIME
The local mean time of all places having different longitudes will be different even within a state, zone or country. If all the places, cities or towns were to follow their own LMT, things would become very difficult and a chaotic situation may arise. What will then be the time followed by the Airlines, Railways, Television, Radio, Internet etc? To solve this problem a uniform time is chosen either by a law or general usage, which acts as a standard time for the country.
The Earth is divided into 24 Time Zones. These run from East to West, like lines of Longitude. When it is 12 Noon in Greenwich, it is 1 o’clock in the afternoon at places in the first time zone to the East, 2 0’clock at places in the second time zone & so on.
Moscow in Russia, is in the third time zone to the East. That means when it is 12 Noon in England, it is 3 o’clock in the afternoon in Moscow.
New Zealand is twelve times zones ahead. This means that it would be midnight in New Zealand when it is Noon in Greenwich England.
New York is five Time zones behind. This means that when it is Noon in England it is 7 o’clock in the morning in New York.
In India, before 1880 each city followed its own LMT. From 1.1.1880 LMT Chennai became popular which was 5h 20m 50s ahead of GMT. From 1.1.1906, + 5:30 hrs Time Zone was adopted for all over India and termed as Indian Standard Time or IST, it relates to 82° 30’E meridian or time zone of + 5:30 hrs ahead of GMT.
Even though all watches show IST in India, the Sunrise and Sunset will vary according to longitude of the place. The Sunrise in the Eastern longitudes, say in Kolkatta will be much earlier than in Jaipur as per IST. But in Hindu astrology it is the concept of LMT, which is more important for all calculations.