The September 2014 Supermoon, the last in a string of three in a row, rises tonight over Toronto, promising a special celestial show for those who care to look closely. While the effect of supermoons tends to be exaggerated (this one is projected to be 15 per cent brighter and seven per cent larger than a typical full moon), the fact that this particular one corresponds with the so-called Harvest Moon gives it an extra bit of drama.

A supermoon takes place when a full moon occurs during its closest approach to the earth (remember: the moon's orbit is elliptical). Because it is quite literally nearer to us, we perceive an increase in brightness and size. The greater intensity is often overstated, but thanks to a well timed moonrise over Toronto, one can expect it to appear particularly large at sunset tonight. The moon always appears bigger as it's first rising, and tonight it starts its ascent roughly 20 minutes before sundown.

Let's send it over to NASA to explain what's called the "moon illusion." This "occurs when the Moon is near the horizon. For reasons not fully understood by astronomers or psychologists, low-hanging Moons look unnaturally large when they beam through trees, buildings and other foreground objects. When the Moon illusion amplifies a perigee Moon, the swollen orb rising in the east at sunset can seem super indeed."

As far as taking in the show goes, just make sure to train your eye to the east between 7:20pm and 8:00pm to take in the moon at its biggest. The supermoon will continue to light up the night after that, but it won't seem quite so majestic as at sunset. If you miss moonrise tonight, you can try again tomorrow, though the moon will not be quite full.

Photo by Yi Jiang in the blogTO Flickr pool.