This weekend’s July full moon over southern Canada won’t deliver as much bang for the buck as the winter full moons do.
The early summer full moons just don’t rise as high in the sky as their winter counterparts, nor do they shine nearly as long.
The reason why you don’t get as many hours of a full moon in the summer as you do in the winter is bit of a trick question.
In the winter, the nights are much longer and so, of course, the full moon will get to cast its light much longer than it does through our relatively short summer nights.
As to why the full moon is lower in the horizon, there’s a long explanation that’s a bit complicated (at least for this writer) involving the orbits of the moon around the earth, the earth around the sun, the ecliptic and so on.
Fortunately, there’s also a simple explanation. It’s because the moon is tracing the path forged by the sun six months previous! And if you’ll recall, six months ago (in January), the sun wasn’t out for long and was kind of low in the sky — so that's what the moon's doing this weekend.
Not to make it more complicated, but it’s the opposite in the Southern Hemisphere, where they are in winter. So if you could get to, say, Australia this weekend, you would find the sun low in their sky, and the days short — but the full moon nice and high overhead and shining a lot longer through the long night!
Here's a slightly more elaborate explanation earthsky.org published prior to last December's full moon: earthsky.org/tonight/december-full-moon-mimics-the-june-sun/.
But back to Canada: if you’re in a big urban area, you might even have to dodge the condos and tall buildings to get a good view of the full moon this weekend.
“This moon will only rise to about 20 degrees above the horizon in Toronto, so tall buildings and trees may block your view,” said Elaina Hyde, assistant professor in York University’s department of physics and astronomy and the director of its Allan I. Carswell Observatory in Toronto.
She also noted that the moon will be “coming to a perigee or its closest approach (to earth) on July 24.”
So that means “during the full moon, it may be a few per cent larger than usual.”
With the moon being low on the horizon, it might also appear even bigger to some people, but it’s just an optical illusion, noted Samantha Lawler, associate professor at University of Regina’s Campion College, with research interests in observational astronomy, planetary science and dynamical modelling of exoplanets.
“You can test it yourself. Hold out your thumb or your finger out in front of you and see how big it is in front of the moon as it’s rising and do it again when the moon is much higher in the sky and you can see it’s actually the same size.
“But I agree. It totally — it totally — looks bigger. It’s an illusion, but you see it that way. Your brain interprets it that way and it’s really neat.”
On a personal note, the Saskatchewan professor said, “I love watching the moon rise. It’s one of my favourite things about living on the prairies, watching the moon rise all the way from the horizon.”
Ontario isn’t quite so flat, and we have a lot more tall buildings getting in the way, but we also do have a lot of very flat lakes that make great backdrops for viewing either sunrises/sunsets or moonrises/moonsets!
Check out this story we did on some of the best places to view sunsets in Ontario.
The official peak of the full moon for the GTA area of Ontario, according to timeanddate.com is Sunday, July 21 at 6:17 a.m. But that's more of a technicality, as it will be pretty full for all the weekend nights.
It's known in some traditions, according to the Farmer's Almanac, as the Buck Moon.
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