September’s Harvest Moon illusion

Hello, Harvest Moon

Image via Wikipedia

Last month, more than 250 people gathered at the Binbrook Conservation Area to see the Persiods Meteor Shower.  Despite clear skies during the day, clouds rolled in obscuring any chances to see the meteors.  However, people were not disappointed because club members put on a good show that made the night worthwhile.  If the weather cooperates this month, you can see a different show in the night sky.

Autumn will officially arrive on the night of Sept. 22 at 11:09 pm.  Only six hours latter, the Harvest Moon will appear, which is the first full moon after the autumn equinox.  The last time this happened on the same night was in 1991 and it won’t again until 2029.

While rising at the horizon, the moon will look more colorful as usual since its light must passes through extra layers of dust in the atmosphere.  It will also look bigger at the horizon, but don’t be fooled because it’s just an illusion.  If you have any doubts, try holding up a dime at arm’s length to the rising moon, while it’s at the horizon and again when it’s overhead. You’ll see that the dime covers exactly the same area of the moon. There are theories that have tried to explain this illusion, but it remains a mystery.

Officially, there is only one Harvest Moon, but you can see its affects again on Sept. 23 and 24.  Normally, the moon rises about 50 minutes later each successive night but at this time of the year, it will rise about 20-25 minutes each successive night.  That’s because the angle of the full moon to the Earth’s horizon is smaller than at any other time during the year.

Here are some important dates for September star gazers.

Sept. 7 — Moon at perigee or nearest to the Earth

Sept. 8 – New moon

Sept. 11 — Venus is only .3° north of the moon

Sept. 13-20 – Look low in the east about an hour before sunrise for a small pinkish speck that is Mercury.  If you look through a telescope you can watch it go through its phases.

Sept. 15 — First quarter moon

Sept. 17 – Hamilton Amateur Astronomers meeting at 7:30 pm, Hamilton Spectator Building, 44 Frid St., Hamilton

Sept. 18 – Look through telescopes and see the moon and Jupiter at Hamilton Amateur Astronomers Grimsby public observing night, 8 pm – 11 pm, Gateway Niagara Information Centre, 424 South Service Rd. located at the south/west corner of the Casablanca QEW overpass in Grimsby. 

Sept. 19 – Look low in the east after sunset through a pair of binoculars and see the blue green planet Uranus close to Jupiter.

Sept. 21 – Jupiter the solar system’s largest planet will be closer to the earth than it has been for the last 47 years and will not be this close until 2022. It will appear bright in the east after sunset and will be an excellent time to view and photograph this gas giant.  Through a telescope you can see details of its bands.  The moon is also farthest from the Earth or at apogee.

Sept. 23 – Full moon

Sept. 30 Last quarter moon

For more information, please see the Hamilton Amateur Astronomers web site at or call (905) 627-4323.


About Mario Carr

Mario Carr has a Physics degree from McMaster University and hosts this blog. He is the director of publicity for the Hamilton Amateur Astronomers and has helped to raise the profile of the group. He writes an astronomy column and appeared on CHCH-TV to talk about the night sky. Mario is the founder of the Carr Marketing Group in Burlington, Ontario and can help with your marketing, communications, publicity and public relations needs. He can be reached at or
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