Since there have been no major eruptions lately, the stratosphere should be pretty free of dust and this eclipse will likely be on the brighter side. To compare eclipses, observers note the degree of darkness using a 5-step scale, named for French astronomer Andr Danjon who devised it. The Harvest Moon Many cultures of the northern hemisphere call the full moon of September the Harvest Moon. It occurs at a time of year when farming peoples are busy gathering in their crops for the coming winter. This is the instant when fall begins in the northern hemisphere and spring in the southern.
Harvest moons are more than just a quaint cultural legacy.
Until about 60 years ago, they offered practical value. Around the time of the autumnal equinox, a Harvest moon rises only about 20 minutes later each successive evening. This means that during this time, for roughly a week strong moonlight pours across farmers' fields in the early evening. Before the days of giant powered combines equipped with floodlights, farmers who had run out of daylight before getting in the crop welcomed the moon's helping hand, however pale it might be. Astronomically, a Harvest Moon occurs because the moon's orbit lies at a shallow angle to the eastern horizon at the end of an early autumn day.