New Delhi: The Sun's magnetic field is soon going to flip by 180-degrees which could lead to changes in climate, storms and even disrupt satellites, scientists have warned. 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-organises itself.
The sun's magnetic field has two poles - like a bar magnet. Every 11 years, the magnetic poles of the Sun reverse at the peak of the solar activity cycle.
"This change will have ripple effects throughout the solar system," said solar physicist Todd Hoeksema of Stanford University. 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.
"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," Solar physicist Phil Scherrer said.
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 kilometres beyond Pluto.
Changes to the field's polarity ripple all the way out to the Voyager probes, on the doorstep of interstellar space. When solar physicists talk about solar field reversals, their conversation often centres on the "current sheet."
The current sheet is a sprawling surface jutting outward from the Sun's equator where the Sun is slowly rotating magnetic field induces an electrical current. The current itself is small, only one ten-billionth of an amp per square meter, but there's a lot of it: the amperage flows through a region 10,000 km thick and billions of kilometres wide. Electrically speaking, the entire heliosphere is organised around this enormous sheet, researchers said.
During field reversals, the current sheet becomes very wavy. Scherrer likens the undulations to the seams on a baseball. As Earth orbits the Sun, we dip in and out of the current sheet. Transitions from one side to another can stir up stormy space weather around our planet, researchers said.
Cosmic rays are also affected. These are high-energy particles accelerated to nearly light speed by supernova explosions and other violent events in the galaxy. Cosmic rays are a danger to astronauts and space probes, and some researchers say they might affect the cloudiness and climate of Earth.
(With inputs from PTI)
Infographic: How the Sun's Magnetic Field works