What so ‘super’ about supermoons anyway?

Another supermoon will illuminate the night sky Saturday, but how extraordinary are they really?

Not very, according to astronomer Paul Mortfield, but he said that doesn’t mean you shouldn’t take a look at the extra-bright moon and take a moment to marvel at the night sky.

A “supermoon is not really anything new, [but] the phrase is new. It’s been around for a couple of years because, again, every year that we have full moons some are a little bit closer and some are a little bit further away from us but not by much,” said Mortfield, chair of the committee that runs the David Dunlap Observatory north of Toronto. “It’s only about a 10 per cent difference but the difference is that somebody decided to call it a super moon and again it’s a great opportunity to go out and look up at the sky.”

The term “supermoon” spiked in newspaper coverage in March of 2011, when media collectively started covering the semi-annual astronomical phenomenon using the catchy word.

Supermoons are more formally known as “perigee moons” and they occur when the moon’s elliptical orbit comes closest to earth. The result is an extra-large, extra-bright moon, especially when it’s rising over the horizon and balloons before the naked eye. If the night is clear, the moon will appear extra luminescent all Saturday night, Mortfield said, despite the fact the true “spike” occurs at 2:09 p.m. EST on Sunday, during peak daylight in Canada.

That said, Saturday’s super moon may be even more spectacular than normal as the moon will be even closer than it was in July: about 1,200 kilometres nearer to earth. But there is a downside for stargazers as well, as the annual Perseid meteor shower collides with the super-bright moon, which means the annual display of shooting stars will largely be drowned out. The big ones will still sparkle across the sky for those who are patient enough to wait, Mortfield said.

“The great thing about the hype of a supermoon is it gets people out to go look at the full moon and look up at the sky and wonder about what’s going on in the universe,” said Mortfield, who returned to Canada to help run the Dunlap Observatory after two decades working in California for Standford University and NASA.

The observatory is not running an event for the supermoon or the meteor shower but its usual programming will run as scheduled.