Tonight's full moon will be the biggest seen in Toronto (and everywhere else on earth!) in the last 18 years. Named the "supermoon," the increase in size has to do with the elliptical nature of our nearest neighbour's orbit. Take it away NASA: "Full Moons vary in size because of the oval shape of the Moon's orbit. It is an ellipse with one side (perigee) about 50,000 km closer to Earth than the other (apogee). Nearby perigee moons are about 14% bigger and 30% brighter than lesser moons that occur on the apogee side of the Moon's orbit."

According to Geoff Chester of the US Naval Observatory in Washington DC, "the full moon of March 19th occurs less than one hour away from perigee — a near-perfect coincidence that happens only 18 years or so...I'd say it's worth a look."

Apologies for the late notice, but the best time to catch this phenomenon is when the moon first rises over the horizon. The supermoon appears 14% larger and 30% brighter your standard full moon, but the illusion created by its relationship with the objects near the horizon line should make tonight's look positively gigantic. So keep an eye out in the east starting around 7:52 p.m. and you might be in for a real treat. And photographers, don't forget to send your shots to the blogTO Flickr pool.

Photo of a near supermoon in 2008 by Hamish Grant.