Scientists shocked to learn that Earth's electric charges are flipped - Details

In space, Earth's magnetic field controls a certain area, which is known as the magnetosphere. Inside this lies an electric field that stretches from the morning side of Earth to the evening side. For the longest time, scientists have thought that the morning side was positively charged while it was negatively charged on the evening side. This is because electric forces move from positive to negative charges. However, a recent study has revealed that this is not the case, and vice versa is true. But this is also only applicable to the equatorial region, and the poles behave exactly as expected. This discovery was made by recent satellite measurements. Researchers from Kyoto University, Nagoya University, and Kyushu University then decided to study how the magnetosphere's electric characteristics are formed and sustained. Their findings were published in Science Daily.

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Researchers created space conditions in a lab

The team created the conditions in near-Earth space using large-scale magnetohydrodynamic (MHD) simulations. They also emulated the charged solar particles by placing a steady stream of high-speed solar wind. Their results backed satellite data, showing that the morning side of the magnetosphere carries a negative charge while the opposite side is positive. Strangely, the pattern was not globally applicable. In the polar regions, the charge polarity follows the traditional idea that the morning side is positively charged, while the evening is negative. But it flipped near the equator. The discovery shows how starkly different the two zones of Earth are.

Corresponding author Yusuke Ebihara of Kyoto University said, "In conventional theory, the charge polarity in the equatorial plane and above the polar regions should be the same. Why, then, do we see opposite polarities between these regions? This can actually be explained by the motion of plasma." He states that the magnetic energy from the sun moves clockwise on the dusk side of the planet and channels toward the poles after entering the magnetic field. "Meanwhile, Earth's magnetic field lines run from the Southern Hemisphere to the Northern Hemisphere -- upward near the equator and downward near the poles."

"This opposing orientation between the magnetic field and plasma flow leads to the reversal in charge distribution between the regions. The electric force and charge distribution are both results, not causes, of plasma motion," Ebihara said. The finding changes how scientists interpret electrical activity in Earth's near-space environment.