'Maverick' sunspot heralds new solar cycle
19:30 07 January 2008
NewScientist.com news service
Maggie McKee

A sunspot with a magnetic field pointed in the opposite direction from others seen previously in the Sun's northern hemisphere appeared on Friday (top, labelled 0981), signalling the start of solar cycle 24.
A new 11-year solar cycle has officially begun, now that a sunspot has been found with a magnetic field pointing in the opposite direction from those in the previous cycle. But researchers are still divided over how active – and potentially damaging to Earth's satellites and power grids – the new cycle will be.
Sunspots are relatively cool regions where magnetic fields from within the Sun have risen up and broken through its surface. They vary in number – going from a minimum to a maximum and back to a minimum again – about every 11 years, the same timescale on which the Sun's magnetic poles reverse direction.
But predicting when the cycles will begin and end and how many sunspots they will produce is a tricky business, says David Hathaway of NASA's Marshall Space Flight Center in Huntsville, Alabama, US. For example, he had predicted that the new sunspot cycle, cycle 24, would be quite active. Since active cycles usually start earlier than average, he expected the cycle's first sunspot to appear a year ago – but it was only observed on Friday, 4 January.

"I'm happy to see this spot," he told New Scientist late on Friday. "For more than the last year, I come in every morning and look at the pictures from SOHO [the Solar and Heliospheric Observatory satellite] and say, 'No, not yet.' And today, someone beat me into work and said, 'Go take a look – I think there's a spot."
The spot – along with a couple of previous magnetic hints that cycle 24 was underway – suggests the Sun is at or near solar minimum, a time when sunspots in the new cycle outnumber the old.

Just when solar max will occur is up for debate, with some research teams predicting 2011 and others 2012. "The bigger the cycle, the shorter the time it takes to get there," says Hathaway. "A number of us believe it's going to be a big cycle and hence it will peak earlier."