It would be much simpler if this were determined by the full Moon closest to the September Equinox, making this year’s Harvest Moon in September and the following full Moon which is today, 18 October, the Hunter’s Moon.
So what exactly is a Harvest or a Hunter’s Moon, and what makes them more significant (if they are) over other full Moons? The significance lies in the idea that September is typically harvest time at mid-latitudes in the United States and that once the fields are cleared the Hunter’s can more easily spot and ‘bag’ their prey. It is also significant in how the Moon rises each evening around the time of full Moon in September and October.
The path or angle
the Moon rises is less steep than at other months so for a few days the Moon rises only about 30 minutes later rather than the 50 or so minutes of later rising time during other months. This in effect means more bright full moonlight later into the evening allowing farmers and hunters to take advantage of the extra light. The change in the angle that the Moon rises, and conversely sets, varies as the angle of the ecliptic changes as the Earth revolves around the Sun going through the cycle of seasons. As this animated graphic is showing this angle changes each month for the same reason that we have seasons – the axial tilt of the Earth.
Like 2 salt grains in the ocean here are two useful resources about the Moon out of the ‘Sagans’ of lunar resources that are out there. (1 Sagan = “billions and billions”
Download the Lunar CRater Observation and Sensing Satellite (LCROSS Storybook)
Download the Lowell Observatory Moon Clock. (PDF 79 Kb)
‘Rock it’ to the Moon in an animated simulation of a crewed Constellation Program mission to the Moon. This is actually a combination of two separate videos that I cut apart and spliced back together to reduce the length. (5m49s)
Just enjoy it!! (1m49s)
And of course Neil Young singing “Harvest Moon”
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.