None. it's like asking how long is midnight.
The Moon moves all the time and it doesn't stop to stay full for a while and then carry on.
It's constantly changing just the same as on Earth. Each instant lasts only an instant and the instant of Full Moon is an instant long.
Zilch amount of time to be technically correct or at least whatever minimum time is allowable so we can say something happened but in practice it looks 'full' for a day either side of the real Full Moon to most folks and sometimes a few Jewish and Muslim dates long ago were a day out because some guy thought the Moon was full when it had a day to go.
Both use the first sighting of the New Moon as the start of a month in the old traditional calendars but they use western style 'business' calendars as well so they stay in step with the rest of the world.
Times are normally given to the nearest minute in astronomical and astrological tables, the Nautical Almanac, the Astronomical Ephemeris etc
Scroll down for 2011 Full Moons with the dates and times in GMT which is the numerically the same as UT. The time may need to be adjusted for where you are. On the second link there is an input box for doing it.
http://moonphases.info/full_moon_calenda… . . . .
http://www.moontracks.com/fullmoonnames.… . . . .
The Moon moves all the time and it doesn't stop to stay full for a while and then carry on.
It's constantly changing just the same as on Earth. Each instant lasts only an instant and the instant of Full Moon is an instant long.
Zilch amount of time to be technically correct or at least whatever minimum time is allowable so we can say something happened but in practice it looks 'full' for a day either side of the real Full Moon to most folks and sometimes a few Jewish and Muslim dates long ago were a day out because some guy thought the Moon was full when it had a day to go.
Both use the first sighting of the New Moon as the start of a month in the old traditional calendars but they use western style 'business' calendars as well so they stay in step with the rest of the world.
Times are normally given to the nearest minute in astronomical and astrological tables, the Nautical Almanac, the Astronomical Ephemeris etc
Scroll down for 2011 Full Moons with the dates and times in GMT which is the numerically the same as UT. The time may need to be adjusted for where you are. On the second link there is an input box for doing it.
http://moonphases.info/full_moon_calenda… . . . .
http://www.moontracks.com/fullmoonnames.… . . . .
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At most, one minute. I wish the Naval Observatory site gave seconds.