Getting up close with the Moon

UP CLOSE: The Moon photographed on the day it was closest to Earth in 2012.
UP CLOSE: The Moon photographed on the day it was closest to Earth in 2012.

The closest full moon of the year will be in the skies tomorrow night, and hopefully visible from some parts of this storm-battered country.

A so-called supermoon happens when a full moon coincides with the closest approach the Moon makes to Earth during its elliptical orbit every month or so.

About 11pm tomorrow the Moon reaches its closest point to the Earth for the current lunar month - its perigee. Then about 20 minutes or so later the Moon officially turns full.

This month the distance at perigee will be 357,000km, the closest perigee of the year. The nearest full moon appears about 14 per cent larger and 30 per cent brighter than the full moon at its farthest point from the planet - the apogee.

Astronomers say the distance in size and brightness cannot be discerned with the naked eye. Many also don't seem to find the whole supermoon idea terribly thrilling.

"It's one of those numerical things that's interesting, but for any practical purpose it's just a non-event," Alan Gilmore, resident superintendent at Canterbury University's Mt John Observatory said.

In fact, as a rule astronomers did not like full moons because their brightness made other things in the sky harder to see.

Gilmore suggested it could be interesting to take a picture of the Moon tomorrow night, then in about six months when the full moon was furthest from Earth take another picture with the same gear and on the same settings "and see if you could spot the difference".

Despite professional indifference, Nasa has been moved to give an assurance that nothing bad comes from supermoons, to counter suggestions they cause natural disasters or drive people crazy.

Nasa planetary geologist Noah Petro said that while the tides might be slightly higher because of the Moon's close approach, the difference wouldn’t be noticeable for the average observer.