Unlike last August this year we will have only one full moon, This month the full moon will not be a “Supermoon” as it was last month, but the Moon will be very close to its fullest when in rises and will “look” full for five nights, versus the usual three nights this month. Observing which “full looking moon” is the true full moon will be a challenge for even the most astute full moon observer.
The traditional full moon name for August is the “Dog Day’s Moon”. The name is derived from the rising of the “dog star” Sirius at dawn. Other names associated with the last full moon of summer are the “Sturgeon Moon”, “Woodcutter’s Moon”, “Green Corn Moon” and “Wort (old-world word meaning plant) Moon”. To the Cherokee it is “the ripe corn moon”. The Oto called it “all the elk call moon”, and for the Zuni it is the “no snow on trial moon”. The Lakota Sioux called it “moon when the cherries turned black”.
The month of August is named after Augustus the first emperor of Rome.
Technically the full moon is only a moment in time, not a twenty-four day. That moment occurs at 7:46pm MDT on Tuesday, August 20 for Aurora, Colorado.
The Moon will look full on the evenings August 19, August 20, August 21, August 22, and August 23. So which is closest to the true full moon? Usually there is an easy way for the casual observer to tell which is which. A full moon always rises opposite the setting Sun. The Moon that rises within a half hour of sunset is the full moon. If the Moon is well above the horizon or has not risen until well after (greater than a half hour) sunset, it is not a full moon even though it looks like one. Let’s test it this month for Aurora, CO.
August 19 The Moon rises well before sunset
Sunset: 7:55pm MDT
Moonrise: 6:43pm MDT
Difference: 72 minutes (Failed, Moon and Sun are not opposite)
August 20 The Moon rises within 30 minutes of sunset
Sunset: 7:49pm MDT
Moonrise: 7:21pm MDT (Full moon occurs at 7:26pm)
Difference: 28 minutes (Pass, Moon and Sun are opposite)
August 21 The Moon rises within 30 minutes of sunset
Sunset: 7:48pm MDT
Moonrise: 7:57pm MDT
Difference: 9 minutes (Moon and Sun are opposite, but the Moon is not a full)
August 22 The Moon rise well after sunset
Sunset: 7:46pm MST
Moonrise: 8:31pm MDT
Difference: 45 minute. (Failed but close, Moon and Sun are not opposite)
This test works usually works every time for any full looking moon, but as you can see the test fails us this month and would actually make us believe the full moon occurs a day later because moonrise and sunset times are closer on August 21!
Note that the Moon rises before sunset on August 20 and after sunset on August 21. Full moon occurs at 7:26pm on August 20 very close to Aurora, Colorado’s local moonrise and sunset times. Local moonrise and sunset times are determined by where you are on the Earth, which is rotating. More often than not full moons do not occur at or near local moonrise and sunset times. When they do the Moon will be look full longer for that location. Check out the Moon on August 23 and see if you can tell it is not a full moon.
A full moon is the only time the Moon is up all night and the only time a lunar eclipse can take place. A full moon also sets in the west opposite the rising Sun. Here in Aurora full moonset over the mountains (west) is on the morning of August 21 at 7:00am MDT. Sunrise is at 6:17 am MDT in the east. The best time to look will be 30 minutes before sunrise. If you have the time, observe the sunrise. They are usually pretty good here in Colorado.
Wishing you clear skies