Full Moon around the globe
If we see a full moon tonight, will there be a full moon on the other side
of the world tomorrow? Meghan, Edmonton, Canada
The Full Moon event, happening in this case at midnight. Diagram courtesy of
Minesweeper and Wikipedia. Drawing modified by author.
That's right, but only according to local times at the two places. For example, folks in Springfield, Illinois saw a Full
Moon on May 19, local time, and those half way around the world at Dhaka, Bangladesh would have seen the Full Moon the next day, twelve hours later, local
time, on the 20th of May — if they could have seen through the Earth.
'Twelve hours later' is a time-zone artifact. Indeed, all people on Earth see the Full Moon
event at exactly the same time
and day. The Full Moon event happened at one time — in this case,
on May 20 at 2:12 am, Universal Time. The people in Springfield saw the
Full Moon, since it was night in Springfield when the event happened.
Those in Dhaka couldn't, since it was morning in Dhaka then.
Further Reading:
Sun
and Moon data, Naval Observatory
(Answered May 26, 2008)
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