Based on historical records, astronomers say the sun this fall ought to be nearing the explosive climax of its approximate 11-year cycle of activity-the so-called solar maximum." But it's not.
"I would say it is the weakest in 200 years," said David Hathaway, Researchers are puzzled. They can't tell if the lull is temporary or the onset of a decades-long decline, which might ease global warming a bit by altering the sun's brightness or the wavelengths of its light.
To complicate the riddle, the sun also is undergoing one of its oddest magnetic reversals on record. Normally, the sun's magnetic north and south poles change polarity every 11 years or so. During a magnetic-field reversal, the sun's polar magnetic fields weaken, drop to zero, and then emerge again with the opposite polarity.
As far as scientists know, the magnetic shift is notable only because it signals the peak of the solar maximum". But in this cycle, the sun's magnetic poles are out of sync, solar scientists said. The sun's north magnetic pole reversed polarity more than a year ago, so it has the same polarity as the south pole.
The giant machine would dwarf all of its predecessors (see 'Lord of the rings'). It would collide protons at energies around 100 teraelectronvolts (TeV), compared with the planned 14?TeV of the LHC at CERN, Europe's particle-physics lab near Geneva in Switzerland. And it would require a tunnel 80-100 kilometres around, compared with the LHC's 27-km circumference. For the past decade or so, there has been little research money available worldwide to develop the concept. But this summer, at the Snowmass meeting in Minneapolis, Minnesota - where hundreds of particle physicists assembled to dream up machines for their field's long-term future - the VLHC concept stood out as a favourite.