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What are the northern lights, and what causes them? Why don’t we see them more often and in more places?
The sun’s magnetic field plays a fascinating role in creating these celestial light shows. As our star approaches its solar maximum, it releases powerful bursts of energy and matter that interact with Earth’s magnetic field, creating the stunning auroras we see near the poles.
Keep reading to explore how this cosmic dance between the sun and Earth creates one of nature’s most magnificent displays.
The Northern Lights and Their Cause
What are the northern lights, and what causes them? The northern lights (also called the aurora borealis) and their counterpart—the aurora australis—are typically visible only from the Earth’s polar regions. The unusual sightings occurred because the sun is approaching “solar maximum”: the peak of its 11-year cycle of activity. Halfway through solar maximum, the polarity of the sun’s magnetic field reverses. As this reversal gets closer, the sun’s magnetic field becomes twisted and tangled, which creates localized magnetic fields. These cause the sun to emit solar flares—bursts of electromagnetic radiation, including visible light, that explode from its surface when magnetic energy is released—and coronal mass ejections (CMEs)—clouds of magnetized plasma that erupt from its atmosphere and can expand to millions of miles across as they travel across space and collide with the magnetic fields of planets such as Earth.
Both solar flares and CMEs occur when the sun’s magnetic field twists, tangles, and explosively realigns itself, a process that drives huge amounts of energy into space. But the kind of energy that each one propels into space is very different. While a solar flare sends light into space, a CME sends solar matter speeding away from the sun, and these high-energy particles sometimes travel toward Earth. If the magnetic field of a CME isn’t aligned with Earth’s, it can disrupt our planet’s magnetic field and create currents that drive the solar particles toward the poles of the Earth. When these particles collide with oxygen and nitrogen in the Earth’s atmosphere, they excite the gases in the atmosphere and cause them to glow.
| The Importance of Earth’s Magnetic Field In The Invisible Rainbow, Arthur Firstenberg explains how Earth’s electromagnetic fields are crucial for life, forming a global network from the ground to the ionosphere. He shows how living organisms sync with these natural electromagnetic rhythms, citing examples such as human brain waves, bird navigation, and hamster hibernation. In his book An Immense World, Ed Yong drives this point home. He writes that Earth’s magnetic field—generated by its core—enables animal navigation worldwide. Many species use this reliable force field for precise navigation and long-distance migration, even in darkness. When solar storms disrupt the field, animal navigation is affected, as seen in increased whale beachings. Animals such as sea turtles can detect specific magnetic signatures to return to birthplaces, aiding species survival. |
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