Once in a Blue Moon

Our Blue Moon Calculator says that in 1999, there are Blue Moons in January and March. Is that true in all parts of the world? After all, previous Blue Moons have fallen on different days in different parts of the world.

Let's start with the basic astronomical facts. The first six Full Moons in 1999 are as follows:

These dates and times have been calculated rigorously using the same methods as those employed by the United States Naval Observatory and by Her Majesty's Nautical Almanac Office. They are given in Coordinated Universal Time (UTC) which is the standard time zone used by astronomers worldwide. It is effectively the same as Greenwich Mean Time (GMT).

Here are those Full Moons again, but with the dates and times adjusted for several major time zones around the world. For each time zone, the two Full Moons which fall in the same calendar month are highlighted.

There are four different sets of circumstances, as the time zone differences change the day and month of some of the Full Moons.

• Eastern Australia and New Zealand have a single Blue Moon, in May.
• Western Australia, Japan, China and eastern Asia have a single Blue Moon, in April.
• Central and western Asia, Africa, the Middle East and most of Europe have two Blue Moons, in January and April.
• Western Europe and the Americas have two Blue Moons, in January and March.

Once in a Blue Moon Who wrote this?

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