How to see the full Harvest Moon 2021 in the UK
Long fall nights are a great time of year to get out and do some astronomy, especially if you want to drink in detail the lunar surface during a harvest full moon.
You won’t have to go to bed late and it doesn’t get too cold, although you might want to take a warm coat and a flask of something warm with you.
But when exactly can you see the full Harvest Moon? And what do you see on its surface? We asked Professor Michael Merrifield, astronomer at the University of Nottingham.
If you’re looking for something a little harder to spot than the Moon, check out the Meteor Shower Calendar for when to catch draconids, or read our beginner’s guide to astronomy.
When is the full Harvest Moon 2021?
The Moon will reach its peak of “fullness” at 12:54 am on September 21, 2021. Although the Moon is technically full for only a moment, you can enjoy great views (weather permitting) for more or less a full day before and after this time.
Why is it called the Harvest Moon?
Full moons all have names, and that name is usually tied to the time of year.
“It’s a tradition to name each of the full moons of the year, and, since we’re now at harvest time (at least in the northern hemisphere), it’s a pretty good way to identify the full moon with the time of year, ”Merrifield says.
How often do full moons occur?
Full moons occur about once every 29.5 days. This is the time it takes for the Moon to orbit once around the Earth. In fact, the concept of months was originally based on the length of the lunar cycle – although in our modern calendar we have adjusted the months to match the length of a year.
We normally see one full moon per month, but since calendar months do not have the same length as lunar months, it is possible to have two full moons in a month. When there are 13 full moons in a year, we call the bonus moon a “blue moon”.
What details can I find when looking at the full moon?
“It really depends on the quality of your eyesight! Without a telescope, you may be able to spot the darker regions called “mares” or “seas”. These are of course not real oceans – they are expanses of ancient lava flows that left these dark spots on the Moon, ”says Merrifield.
“With a pair of binoculars or a small telescope, you should be able to start spotting many individual craters. Away from the full moon, looking near the terminator – where night turns to day on the moon – should help, as this is where the shadows are longest, helping to spot these features.
There are a few craters that you can spot with the naked eye on the surface of the Moon. If you are in the Northern Hemisphere, look slightly to the left of the center of the Moon and you will see a bright crater named Copernicus. To the left of Copernicus, you’ll see the Aristarchus Crater, and towards the bottom is Tycho.
If you are in the southern hemisphere, the Moon will appear upside down.
About our expert, Professor Michael Merrifield
Michael is professor of astronomy at the University of Nottingham. He studies the formation and structure of galaxies, cosmology and X-ray and gamma-ray astronomy.