The earth is a big place, and it is a different time everywhere all around the world. So even though a lunar phase is occurring at a split instant up in the cosmos, in order to find out what time it occurs in your particular location, you need to convert the time given for the general lunar phases from the ready reckoner or other lunar calendar to your particular time zone.
You can either do this manually by following the instructions below or go to the Time Zone Converter, a web based application that performs the calculation for you.
Greenwich Mean Time or GMT or Universal Time (UT) has been chosen as the 0 point.
Greenwich Mean Time = 0 hours.
Every other location in the world is compared to GMT and has a standard number of hours that are either added or subtracted to the GMT time.
|Subtract the Hours Zones||Add the Hours Time Zones|
Brazil Zone 2
USSR Zone 3
If we want to convert 12 noon GMT to Australian Eastern Standard Time, looking at the table above we would observe that Australia Eastern Standard Time is +10 hours. Therefore we add 10 hours to 12noon GMT.
12 noon + 10 hours = 10pm
Therefore 12pm GMT = 10pm AEST
Now what if the time you need to convert is 6pm GMT. We now have to add 10 hours to 6 am which means we will go forward into the next day.
First we convert 6pm to 24 hour clock mode which still = 18:00
Then we add 10 hours to the 6pm time, So 18:00 + 10:00 = 28:00 hours
Next we subtract 24:00 hours from 28:00.
28:00 – 24:00 hours = 4:00 hours which corresponds to 4am the next day.
Therefore 6pm GMT time = 4am Australian Eastern Standard Time the next day
What if you are living in Los Angeles, which is Pacific Standard Time, a difference of -8 hours
To convert 12 noon GMT time to PST, simply subtract 8 hours from GMT.
GMT 12 noon – 8 hours = 4am
But what if it was 3am GMT that you wanted to convert to Pacific Standard Time.
Well, in this case we convert to 24 hour clock mode again as we will be jumping days, but backwards this time.
So 3:00 hours – 8:00 hours or 27:00 – 8:00 = 19:00 hours or 7PM, the previous day.
Another factor to take into account is Different locations around the world enforce Daylight Savings or Summer Time at differnt times throughout the year. You will know when this is happening because everyone will be moving their clocks backwards or forwards.
Daylight Savings time alters the number of hours to adjust GMT by.
If we use Example 1 again, and we were using Australian Eastern Daylight Time, we would be adjusting the time by +11 hours, therefore 12 noon GMT + 11 hours = 11 pm Australian Eastern Daylight Time.
There are various sites on the net on which you find out when Daylight Savings come into effect for your time zone, these sites will usually also list time zone conversions, so you can do your calculations there or just check your results if you need too.
After some practise, this calculation becomes very straight forward.