The moon's orbit is elliptical, and as it follows its path, one side of the ellipse, known as perigee, passes about 50,000 kilometers (31,000 miles) closer than the on the other side -- apogee. A perigee full moon appear around 14 percent bigger and 30 percent brighter than an apogee full moon.

Geoffrey Wyatt from Sydney Observatory says this upcoming full moon, which NASA's website says will be of "rare size and beauty," will rise at about 08:00 pm (AEDT) on Saturday. But it becomes full on Sunday morning at 05:10 am (AEDT), one hour before lunar perigee.

"So, Sunday morning, those people who are up early or getting home super late, look to the west and you'll see the biggest moon for 18 years," says Wyatt. The last time the full moon was so big and close to Earth was in March 1993.

"You've got two cycles here. You've got 29 and a half days between full moons and then you've got 27 and a half days from apogee to apogee," he says. "That difference builds up and although you get a perigee every month, to get it at minimum distance takes about 18 years."

Perigee full moons also usually bring extra-high tides, but Daniel Jaksa, co-director of the joint Australian Tsunami Warning Centre says they will probably be a fraction of one per cent higher than normal.

Meanwhile an Auckland-based mathematician known as the 'Moonman,' Ken Ring, has warned the perigee moon will cause another major earthquake in Christchurch, New Zealand. Ring claims he predicted Christchurch's 22 February quake by studying the moon.

But, Wyatt says he'd like to see some scientific proof to back the Moonman's claims. "For a few weeks now we've been hearing people talk about 'Moonageddon,'" he says. "It's depressing to hear people saying this sort of thing. There is absolutely no evidence for a causal link between the phases of the moon and earthquake activity. It's something you might find in 'Tom's Backyard Mechanic's Book of Celestial Tomfoolery', but you're not going to find that in peer-reviewed journals."

Jaksa agrees.

"You only have to look at the major energy source that's driving the tectonic process and it's not the moon. It's the convection currents in the mantle as the Earth tries to cool down from its core outwards that drives plate tectonics."

Wyatt says the claims are a symptom of the human condition. "People blame things on the alignment of the planets because they want an explanation, but it's not the moon's fault."

Discovery News — A powerful solar eruption has disturbed radio communications and could disrupt electrical power grids, radio and satellite communication in the next days, NASA said. A strong wave of charged particles emanating from the Jupiter-sized sun spot, the most powerful seen in four years, has already disrupted radio communication in southern China.

The X-class flare -- the largest such category -- erupted at 1:56 a.m. GMT Tuesday (10:56 p.m. EST Monday), according to the US space agency. "X-class flares are the most powerful of all solar events that can trigger radio blackouts and long-lasting radiation storms," disturbing telecommunications and electric grids, NASA said Wednesday.

Geomagnetic storms usually last 24 to 48 hours -- but some could last for many days, read a statement from the US National Weather Service. "Ground to air, ship to shore, shortwave broadcast and amateur radio are vulnerable to disruption during geomagnetic storms. Navigation systems like GPS can also be adversely affected."