They appeared unexpectedly and soon disappeared again: the northern lights. But how do these celestial spectacles actually come about?
On clear winter nights, Northern Lights (Aurora Borealis) can usually be seen in northern countries such as Finland or Norway . Although it rarely happens, the light spectacle could also be seen over parts of Germany at the end of April and beginning of November 2023.
What is responsible for the glow in the night sky?
First: The fact that the northern lights can be observed in our latitudes has nothing to do with climate change or other factors that can be influenced by humans.
The light play is triggered by high-energy solar wind particles that are thrown into space at high speeds by eruptions on the sun’s surface and hit the Earth’s magnetic field.
The particles need up to two days to complete their 150 million kilometer journey. When the particles collide with oxygen or nitrogen molecules in the Earth’s atmosphere, energy is transferred. The lights that can be observed arise when this energy is released back into the atmosphere.
What does the color of the northern lights depend on?
What’s noticeable: Sometimes the northern lights don’t shimmer green, but rather red. Where does it come from?
Rainer Kresken is an engineer at the Esa space agency and head of the Starkenburg Observatory in Heppenheim. In an interview with t-online, he said: “Green northern lights are usually generated by oxygen at an altitude of 80 to 150 kilometers.”
At an altitude between 150 and 600 kilometers, nitrogen atoms would produce red or blue colors. “Since we are quite far away from the polar regions in Germany , we can only see the northern lights in the higher layers of the atmosphere,” says Kresken.
If you want to increase your chances of seeing the northern lights, it’s best to travel to the far north in the dark winter months. The probability of seeing the colorful spectacle in the sky then increases in any case. “Basically, it’s good to be in a really dark place,” he said. “In the city you don’t really have a chance.”
So whether you will actually see the Northern Lights is literally up in the air – but there is help.
What helps when searching for the northern lights?
Anyone looking for the Northern Lights has to rely on luck. Or use the “Hello Aurora” app from two Icelandic inventors. This shows whether the Aurora Borealis will be visible at your location.
To do this, the application uses complex information about weather , magnetic fields and solar storms and calculates the probability of northern lights. And not just for the moment, but also for the days to come. This should make it easier for northern lights hunters to search for the rare phenomenon.
According to the Swedish tourism agency Visit Sweden, the app works everywhere in the world. It uses data from the magnetometers that are closest.
An international community of aurora hunters makes photos and sighting reports available in real time via the app.
Are northern lights dangerous?
The northern lights themselves are not dangerous. In addition to the fascinating plays of light in the sky, the northern lights can also be a harbinger of an invisible danger from space: solar storms. Scientists keep warning about this.
Solar storms can severely impact the earth’s magnetic field. The result would be disruptions to telecommunications on Earth and blackouts.
When the sun is particularly active, so-called mass ejections occur. Scientists talk about this when plasma from the sun is ejected into space with a mass of tens of billions of tons.
The plasma consists of electrons, protons and the nuclei of heavy elements such as helium, oxygen or iron . The ESA describes this as a “highly charged mixture of particles that can endanger people and technology and destroy the infrastructure in space and on Earth.”This scenario has not yet occurred. Until now, the Northern Lights have been a light spectacle in the night sky that is well worth seeing. And it should stay that way.