Home STEM How Do Northern Lights Happen?

How Do Northern Lights Happen?

by Eric Zeng

Northern lights are a very spectacular phenomenon when we see them on camera. These lights span across the whole sky allowing for some pretty cool-looking photos at night.

The other term for Northern Lights is Aurora since they don’t only occur in the Northern Hemisphere, they occur in the Southern Hemisphere also.

Auroras are lights in the night sky that only appear near either poles of the Earth. They are visible every night in regions that have a latitude of at least 66.5 degrees north of the Equator or 66.5 degrees south of the Equator. The Northern Hemisphere of the Earth calls them Aurora Borealis or Northern Lights. The Southern Hemisphere calls them Aurora Australis or Southern Lights.

The formation of these incredible displays of light starts with the sun. The sun is made of very hot gasses that are made of particles charged with electricity called ions. These ions stream from the sun’s surface continually and are called solar wind. As the solar wind reaches Earth, it hits Earth’s magnetic field. Most of the solar wind is blocked by this field protecting Earth and forced around it, traveling farther out of the Solar System. Without the magnetic field, these solar winds would blow away the atmosphere and there would be no life on Earth.

Even though most of the solar wind is blocked by the magnetic field, there are some ions that get trapped in holding areas around the Earth shaped like rings. These areas are in a part of the atmosphere called the ionosphere that is centered around the Earth’s geomagnetic poles. These poles mark the axis tilt of the magnetic field of Earth. These poles are about 1300 Kilometers (800 Miles) from the geographic poles.

The ions then collide with the oxygen and nitrogen in the Earth’s ionosphere. The energy released from these collisions causes a glowing halo around the poles called an aurora. Auroras happen most often in 97-1000 kilometers (60-620 miles) above the surface of the earth. How active the aurora is depends on how strong the solar wind is.

The color of the Aurora depends on how high up it is and the types of atoms involved in the collisions. For example, if solar wind strikes oxygen at very high altitudes, it makes a red color. The one we are most familiar with is the green, yellow, and blue colors. These colors occur when solar wind strikes oxygen lower in the atmosphere.

Auroras are very amazing displays of light. Although I haven’t been lucky enough to see them for myself, I would recommend you to go somewhere that is either close to the north pole or south pole to see them for yourself.

Source:

“Aurora.” Home - National Geographic Society, www.nationalgeographic.org/encyclopedia/aurora/#:~:text=1%2F5,appear%20in%20lower%20polar%20regions. Accessed 27 Oct. 2023.

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