Washington: Measurements from NASA-supported observatories suggest that the sun`s vast magnetic field is about to flip.
"It looks like we`re no more than three to four months away from a complete field reversal," solar physicist Todd Hoeksema of Stanford University, said.
"This change will have ripple effects throughout the solar system," he said.
The sun`s magnetic field changes polarity approximately every 11 years.
It happens at the peak of each solar cycle as the sun`s inner magnetic dynamo re-organizes itself.
The coming reversal will mark the midpoint of Solar Cycle 24. Half of "solar max" will be behind us, with half yet to come.
Hoeksema is the director of Stanford`s Wilcox Solar Observatory, one of the few observatories in the world that monitors the sun`s polar magnetic fields.
The poles are a herald of change. Just as Earth scientists watch our planet`s polar regions for signs of climate change, solar physicists do the same thing for the sun.
Magnetograms at Wilcox have been tracking the sun`s polar magnetism since 1976, and they have recorded three grand reversals-with a fourth in the offing.
Solar physicist Phil Scherrer, also at Stanford, describes what happens: "The sun`s polar magnetic fields weaken, go to zero and then emerge again with the opposite polarity. This is a regular part of the solar cycle."
A reversal of the sun`s magnetic field is, literally, a big event. The domain of the sun`s magnetic influence (also known as the "heliosphere") extends billions of kilometers beyond Pluto.
Changes to the field`s polarity ripple all the way out to the Voyager probes, on the doorstep of interstellar space.