Greenwich meridian it is 12 noon than what is the time at the given below places a) Mumbai 78 degrees East b) Sydney 150 degrees East longitude c) Chicago 90 degrees West longitude
Answers
Answer:
Since 360 divided by 24 is 15, 30 degrees east will be two hours before Greenwich Mean Time (today, called UTC). But since the earth is divided into time zones that are following the boundaries of the countries, it is not evident that it is exactly two hours. For example, the UTC+1 time zone extends from Kirkenes, in north Norway, to Vigo in Spain. That is: 38 degrees of longitude! It means that noon is, in Vigo, two hours and forty minutes after Kirkenes.
What could be used then, is the Greenwich Hour Angle (GHA). Once corrected for the Equation of Time, it can give you the time of noon at a different place on earth.
The Equation of Time is because the path of the earth around the sun is not a perfect circle but an elliptic one and, therefore, time is only 24 hours as a yearly average. In-between, it can be from about 24h 15min, to 23h 45min.
This is something I did, in the time before the GPS, when I was still using a sextant on my sailboat.