I see a supermoon rising

While astronomers and other scientists suggest everyone just take a chill pill and enjoy the prospect of a larger moon on March 19, US astrologist Richard Nolle believes it heralds disaster.

Supermoons are closer to Earth and occur every 10 to 20 years - the most recent being in 1955, 1974, 1992 and 2005.

On March 19, the moon will be 356,577 kilometres from Earth, the closest it has been since 1992.

The lunar perigee, or supermoon - a term that Mr Nolle said he coined in 1979 - takes place because the moon does not orbit the Earth in a perfect circle, but in a slightly elliptical manner.

"Supermoons, in fact, have a historical association with strong storms, very high tides, extreme tides and also earthquakes," Mr Nolle told ABC Radio this week.

"Supermoons are like eclipses. We have roughly five to six per year ... and so it can be very close to Earth but we don't have to have one at the maximum close approach to have a notable effect."

Mr Nolle said the most recent supermoon on February 18 had an impact on Earth from February 12 to 21. He drew a link between the lunar phenomenon and the Christchurch earthquake, which hit New Zealand on February 22.

He also linked the 1948 Ashgabat earthquake in Turkmenistan, the eruption of Mount Pinatubo in the Philippines in 1991 and 2005's Hurricane Katrina in the United States to periods of supermoon activity.

But Mr Nolle's theories were dismissed by astronomers and seismologists, who said natural disasters happen regardless of whether there's a supermoon or not.

"I would say that the chances of disaster from this supermoon is as great as the chances that the world will end on December 21 next year," said Australian Astronomical Observatory's research astronomer Simon O'Toole, citing interpretations of the Mayan calendar that suggest December 21, 2012 is the day when the world ends.

"So, basically, zero."

Dr O'Toole said there was only a 1 to 2 per cent difference in the distance of the moon from Earth when a perigee (closest) or apogee (furthest) occurs, and so, instead of encountering a bad moon on the rise on March 19, we would only experience a "slightly higher tide" and of course, a larger-looking moon.

"The gravity of the moon is tugging on the Earth and causing a slight sort of distortion as the moon orbits the Earth and that leads to tides eventually.

"But I think that the main thing that we will expect to see [on March 19] is that the moon will look very slightly bigger ... and we may not even be able to perceive that it is bigger."

Clive Collins, a senior seismologist at Geoscience Australia agrees, said that, while many scientists have studied whether there is a link between lunar cycles and seismic activity, none have found any clear connections.

"You get tidal effects which do cause changes in the stress on the Earth but it's not shown that you can predict that earthquakes occur at certain lunar cycles," he said.

"There have been some indications and some circumstances when you get small earthquakes during high tides where you've got lunar and solar gravitational effects occurring at the same time ... but there is no clear correlation, particularly with large earthquakes."

Conspiracy theory or not, Dr O'Toole is certain that the supermoon event will generate assumptions about its impact.

"I think what will most likely happen is the supermoon will come and go next week and then people will look back and say, 'Ah-ha! On March 18 or 19 or 20, all of these things happened and it must have been caused by that.'

"And of course if you look back a couple of weeks ago, you had a giant earthquake in Christchurch. And that was not related to anything like that. It just happened.

"The Earth is a dynamic system - you get all sorts of events independent of the moon and the sun."

Further reading:

The links between astronomy and tides (The US's National Oceanic and Atmospheric Administration)

When do lunar perigees and apogees occur? (Geoscience Australia)