The Northern and Southern Lights

The Aurora Borealis and Aurora Australis, commonly known as the Northern Lights and the Southern Lights, are popular atmospheric phenomena that many people desire to witness. But what exactly are the Northern and Southern lights, and how can they be witnessed?

The Northern and Southern lights are named after the Roman goddess of Dawn, Aurora, by Galileo Galilei. In fact, when naming this phenomena, Galileo had the misconception that the Aurorae were caused by sunlight. But in reality, this is not the case. Essentially, Aurorae are caused when solar wind particles from the Sun are trapped in the Earth's atmosphere. When magnetic reconnection occurs, a process in which solar wind particles are accelerated towards the poles of the Earth's atmosphere, the particles collide with atoms and molecules. These types of interactions result in a release of a burst of light, which we witness as the Northern and Southern Lights. For example, the image above shows us the Northern Lights occurring on the Earth, from the perspective of space. The Aurorae are usually witnessed from locations close to the Earth's poles, but this can vary depending on the intensity of the solar winds. Although they can be viewed at all times of the year, they are usually most active in the months of March and September. Furthermore, it is better to view them during the winter months, rather than the southern months, because there are more hours of darkness in the winter and the skies are generally darker, making it easier to spot the Aurorae. Another fact to note is that while the Northern and Southern Lights can occur at any time of the year, they can only be witnessed during the nighttime.

The colors of the Northern and Southern Lights are affected by the altitude. For example, you will typically see violets and reds when they are at about below 60 miles (100 km), while green colors are typically seen when they are about 60 to 150 miles (100-240 km) in altitude. Although they might seem frightening at first, the Northern and Southern Lights are not dangerous to humans. But despite this, they can still have harmful effects on our infrastucture. For example, Aurorae typically occur during geomagnetic storms, which can cause power outages depending on the intensity.

Although people may assume that the Aurorae are unique to Earth, scientists have actually observed Aurorae on other planets as well, such as Mars, Jupiter, and Saturn! For example, on the left, an Aurora is seen on Jupiter. They also theorize that Aurorae may appear on Uranus and Neptune as well, though none have been witnessed.

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Bibliography

Fox, K. (2021, January 29). Aurora: Illuminating the sun-earth connection. NASA. Retrieved August 15, 2022,

from https://www.nasa.gov/aurora

Frequently asked questions: The northern lights. Hurtigruten. (n.d.). Retrieved August 15, 2022, from

https://global.hurtigruten.com/inspiration/experiences/northern-lights/faq/

Morrow, A. (2016, June 29). Hubble captures vivid auroras in Jupiter's atmosphere. NASA. Retrieved August 15,

2022, from https://www.nasa.gov/feature/goddard/2016/hubble-captures-vivid-auroras-in-jupiter-s-atmosphere

What are the Northern Lights? The Library of Congress. (n.d.). Retrieved August 15, 2022, from

https://www.loc.gov/everyday-mysteries/astronomy/item/what-are-the-northern-lights/