Full moon occurs when the sun is on one side of the earth and the moon is directly opposite the sun on the other side of the earth. That is going to happen on May 17th at 11:09 Universal Time.
So what is Universal Time and why do we use it?
If I wanted to tell everyone in every country what time of the day the moon was going to be full, I could write a great big list for every time zone throughout the world, OR I could tell them what time it will happen in England (standard time, not daylight savings time)--and call that Universal Time (UT).
In Wisconsin, if it is daylight savings time, you turn the clock back 5 hours from UT; if we do not have daylight savings time, you subtract 6 hours.
The moon will pass that spot where it is perfectly opposite the sun at 11:09 UT.
11:09 -5 hours = 6:09
So the moon will be perfectly full at 6:09 Central Daylight Time on the morning of May 17th, 2011. But wouldn't you know it? The moon is going to set and disappear below the horizon about a half an hour before that!
What's to do?
The moon is going to be large and beautiful on the evening and morning of the 16 and the 17th...so go outside and enjoy the big, full moon then. It will rise in the east at dusk and set just before dawn. It is a great time to go outside for a hike--with the moon so bright, you may not need a flashlight!
P.S. Some of you might be interested in knowing that Universal Time is also known as Greenwich Mean Time. You may have studied in your geography classes that the Prime Meridian passes through Greenwich, England--they chose the time of day on the Prime Meridian as our Universal Time.