How to Calculate Moonrise
Whether you are out on the water in your boat or out in your backyard with your telescope, you may want to know the time that the moon will rise. The moonrise occurs almost an hour later each day, and calculating it involves using the Tables from the Nautical Almanac for two days and calibrating to current conditions.
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Things You'll Need
- The Nautical Almanac
- Calculator
- Your current position
- Correct time from radio station WWV or WWVH
Instructions
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1
Record your latitude and longitude and open the Nautical Almanac to the page for the date for which you want to determine moonrise. Moonrise times will be listed on the page on the right side of the book.
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2
Record the Local Mean Time (LMT) of moonrise for the smaller of the two listed latitudes -- or your exact latitude, if listed -- to determine which bracket is yours. Repeat this procedure for the following evening as well.
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3
Turn to page xxxii in the front of the Almanac and use Table I to find the correction for your latitude. Record the correction.
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4
Add the correction to both days. If the corrected time is not between the times shown in the Almanac for both days, then you will have to subtract the correction from both days.
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5
Convert the LMT that results from the correction to Zone Time. The correction will give you the time of moonrise at the Greenwich Meridian.
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