The Sun's magnetic field is expected to flip upside down within weeks as its north and south poles swap sides.
The phenomenon, which will send "ripple effects" throughout the solar system, happens once every 11 years as the solar cycle reaches its peak.
It will be observed throughout the heliosphere - the vast region of space affected by the Sun's magnetic field, which extends billions of miles beyond Pluto.
The swap could cause intergalactic weather events such as geomagnetic storms, which can cause radio blackouts and interfere with satellites.
The heightened solar activity it coincides with is also expected to give stargazers a better glimpse of the aurora borealis, or Northern Lights.
Todd Hoeksema, a scientist at Stanford University's Wilcox Solar Observatory, said the polar reversal takes place as the Sun's magnetic field moves north or south from the equator, eroding the existing pole as it does so.
"It's kind of like a tide coming in or going out," he said. "Each little wave brings a little more water in, and eventually you get to the full reversal."
Latest measurements show the Sun technically has two south poles, caused by its two hemispheres being out of sync.
Phil Scherrer, who works with Mr Hoeksema at the observatory, said: "The north pole has already changed sign, while the south pole is racing to catch up.
"Soon, however, both poles will be reversed, and the second half of solar max will be under way."
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Before reading this article, were you even aware this happens?