Dreaming of an aurora

Nasa's Solar Dynamics Observatory snapped this X-ray photo of the sun on Sunday evening (NZT). The dark arc near the top right edge of the image is a filament of plasma blasting off the surface - part of the coronal mass ejection. The bright region is an unassociated solar flare. When particles from the eruption reach Earth tonight or tomorrow, they may trigger an auroral display. Photo by NASA.

Astronomers witnessed two "huge" flares, explosions and mass ejections of filament from the sun on August 1 and media have since been reporting that Earth's magnetic field could be hit by a solar storm likely to spark spectacular displays of aurora australis, or the southern lights, as early as last night.

But Associate Prof Neil Thomson, from Otago University, said there was no knowing how impressive any night-time display might be.

He said the predictions were possibly wishful thinking from people keen to see the end of a particularly long solar minimum.

"From what I have read and understand, there is not really any support for a "solar tsunami" as is being reported in the international media."

It seemed a spectacular solar light display in New Zealand was unlikely - especially as the solar flares were about 1000 times smaller than the biggest solar flare, recorded by scientists in 2004, he said.

The flare might produce aurora tonight or tomorrow night, but it was unlikely to be anything as spectacular as aurora seen over the South Island in 2004.

He based his view on information from several astronomical websites including the United States' National Oceanic and Atmospheric Administration's Space Weather Prediction Centre, which predicted active to minor storm activity levels with a "slight chance" of a major storm on August 4 and 5, when the mass ejection of filament from the second solar flare arrived at the Earth's magnetic field.

Solar minimum was the period of least solar activity in the 11-year solar cycle of the sun.

During that time, sunspot and solar flare activity diminished.

The present solar cycle had hit its lowest point of activity in 2008 and 2009, but the sun was taking an unusually long time to become more active, Prof Thomson said.

"People have been asking what's wrong with the sun."

It could be the case, that people were so keen to see the end of the solar minimum, they were reading more into the sun flare than was actually there, he said.