Summer’s end is on the horizon, and the arrival of autumn will be heralded by a Harvest Moon on September 16, when there will also be a penumbral lunar eclipse. The full Harvest moon will peak at 3:05 p.m., but will appear full to casual skywatchers a day before and after the actual full moon date.
The term “Harvest Moon” refers to the full moon that falls nearest to the autumnal equinox, which will take place on Sept. 22. This full moon will also be a penumbral lunar eclipse, although the effects may not be visible to the naked eye.
A nighttime full moon provides a brilliant natural light source, so many people use this monthly event as a reason to take a nighttime hike or stroll on the beach. It’s also an opportunity to look at some of the major features on the surface of the moon, many of which are visible without a telescope.
A full moon takes place when the moon is on the side of the Earth opposite from the sun. The exact moment when the moon is officially “full” comes when the three bodies — the Earth, the moon and the sun — fall in a straight line, and the Earth-facing side of the moon is completely illuminated by sunlight.
Sometimes, when these three bodies line up, the Earth’s shadow blocks the sunlight from falling onto the surface of the moon. On Sept. 16, the moon will pass through the very outer region of the Earth’s shadow, in what is known as a penumbral eclipse. This will only create a very faint dimming of the full moon, which may not be visible to most skywatchers.
The eclipse will be visible to varying degrees across Europe, Africa, Asia, Australia and the Western Pacific. The point of maximum eclipse will take place at 18:54:20 Universal Time (UTC), or 2:54 a.m. EDT (1854 GMT). Viewers in other parts of the world will enjoy a normal full moon.
This year’s Harvest Moon will occur at 3:05 p.m. EDT on Sept. 16; however, as is typically the case, the moon will appear full for a few days before and after that day.
Where do the Moon names come from?
Throughout history, different cultures have given unique names to the full moons based on the time of year that they occur.
“People used to track the passage of time based on the moon,” Andrea Jones, an education specialist for the Planetary Science Institute, told Space.com. “The moon is a very obvious timekeeper for ancient civilizations.”
For that reason, there are many different names for each full moon, depending on what part of the world you happen to be in. The Harvest Moon is a name that arose in the Northern Hemisphere, where autumn begins in September (unlike in the Southern Hemisphere, where September marks the start of spring). The Harvest Moon is followed by the Hunter’s Moon, the Beaver Moon and the Cold Moon.