Introduction to the Northern and Southern Lights
In recent years, there has been increasing interest in the almost psychedelic vision of bright green and purple lights dancing across the sky. The desire to get a glimpse of what is officially known as the Aurora Borealis and Aurora Australis has led to special tours, viewing parties, and numerous tracking apps.
What Causes the Different Colors?
Huge explosions on the surface of the sun, so-called solar storms, regularly throw out huge streams of electrically charged particles. Some of this plasma eventually migrates to Earth and is drawn to the planet’s magnetic poles. These particles then collide with atoms and molecules in Earth’s atmosphere, essentially heating them. The different colors of light depend on the elements in the atmosphere. Oxygen, which makes up about 21% of the atmosphere, gives off a green color when heated, while nitrogen turns the color light purple, blue, or pink. Interactions with oxygen at very high altitudes can even give the lights an intense scarlet color, but this is relatively rare.
Where Are the Lights Visible?
The light show is usually only visible near the Arctic Circle – or, in the case of the Aurora Australis, around Antarctica. But we just ended an 11-year cycle of powerful sunspots and flares, known as solar maximum, in which lights illuminated the sky much farther from the poles. Current exhibitions have been seen in Hungary, Switzerland, and the US state of Florida as well as in southern Australia and New Zealand.
Are the Northern Lights Dangerous?
Researchers at the Kjell Henriksen Observatory, the world’s northernmost auroral station in Svalbard, Norway, have studied the solar energy particles contained in the northern lights and their potential to damage the ozone layer. Noora Partamies, an atmospheric physicist at the observatory, told that there is sometimes a "major ozone depletion" in the polar regions due to the aurora borealis. The ozone layer, that thin layer of gas about 15 to 30 kilometers above Earth’s surface, is an important shield that protects us from the sun’s harsh radiation.
Do Northern Lights Only Exist on Earth?
Although they are harder to see, auroras have been observed on most planets in our solar system. Their size and intensity are related to the planet’s atmosphere and the strength of its magnetic field. The light show is more spread out on Mars, which has a more localized field instead of an Earth-like global magnetic field, especially in the southern hemisphere. A diffuse green glow seems entirely possible in the Martian sky, at least when the sun throws off high-energy particles.
Why Shouldn’t You Whistle at the Northern Lights?
Possible sightings of the Aurora Borealis were reported as early as 3,000 years ago in a Chinese text from the 10th century BC. It was recorded in the 1st century BC, in which a “five-colored” phenomenon in the northern night sky was described. Over the centuries, these natural phenomena have inspired awe-inspiring societies around the world. The name itself is associated with Aurora, the Roman goddess of the dawn, and Boreas, the Greek god responsible for the north wind. And the miraculous lights were often interpreted as prophecy or signs from the gods. In Native American and Inuit myths, the lights were associated with creator gods, evil giants, or the spirits of stillborn babies and dead ancestors. For many cultures, from the Saami of Lapland to North American tribes, the lights were feared and respected – something as simple as whistling, for example, could summon the wrath of spirits to descend and kidnap the thoughtless perpetrator.
