A northern lights display near the jardin du Lautaret

Press release Research, Scientific and Technical Culture
March 7, 2023
Northern Lights, Galibier webcam, February 27, 2023
It was around 10 p.m. on Monday, February 27, 2023, when a glow appeared above the summit of Grande Chible. Surprising. Rare in this region. And yet, this reddish-purple halo was indeed an aurora borealis. It was captured by the webcam installed byUniversité Grenoble Alpes, The jardin du Lautaret Valloire Tourisme on the Galibier ridges. At the same time, this glow was also captured at Collet d'Allevard, confirming the diagnosis!

Let's rewind! What causes the Northern Lights and why are they rarely seen at these latitudes?

In addition to sending us light, the Sun continuously sends electrically charged particles, mainly protons and electrons. This flow of particles, called the "solar wind," varies greatly over time. It can become more intense during solar flares. There are more particles, and they move faster. On February 25, a strong solar flare ejected a large stream of particles from the Sun toward Earth.

These particles travel at speeds between 300 and 500 km/s, sometimes exceeding 1,000 km/s during strong eruptions. It takes them between two and three days to reach Earth. Upon arrival, they "encounter" the Earth's magnetic field and follow a complex path that brings them to an oval centered around the Earth's magnetic poles, slightly offset from the geographic poles. This oval varies in size depending on solar activity. There is one in the north and another in the south. The northern oval, which is the most commonly observed, usually passes over northern Scandinavia, Iceland, the middle of Greenland, and northern Canada. On the Russian side, it is offset due to the inclination of the magnetic field and passes instead over the Arctic Ocean. On February 26 and 27, 2023, the particle flow reached Earth and we began to observe its effects. The oval expanded and the auroras intensified. The southern border of the northern oval descended to the latitudes of England and the Canada-US border.

How could they also be observed in Brittany or even at the Col du Galibier?

In fact, they occur at very high altitudes, between 100 km for the green color and 220 km for the red color. A quick geometry calculation shows that the aurora seen at Galibier was actually above Sheffield in England, about 1,000 km from our mountains. This is why we only saw red, emitted at a higher altitude.

Even stronger events are possible. In 1859, a very strong series of solar flares occurred and aurora borealis were observed in Cuba and India. It is important to study them because these particles, in addition to producing magnificent lights, can disrupt our technologies, electrical networks, satellites, GNSS (global navigation satellite systems), communications, etc.

This field of study is called space meteorology.

The Northern Lights can be seen in France approximately once every ten years. Webcams, such as those installed byUniversité Grenoble Alpes, The jardin du Lautaret Valloire Tourisme at Galibier, can become valuable tools for scientific analysis in the field of space meteorology.

Mathieu Barthélemy, professor at UGA, director of MPLS-AD, and deputy director of research at CSUG

Article written by Mathieu Barthélemy, specialist in space meteorology and auroral physics. He is a professor atUniversité Grenoble Alpes IPAG-PhITEM), director of the Maison pour la Science en Alpes Dauphiné, and deputy director of research at the Grenoble University Space Center.

This article discusses the Northern Lights, but what is the difference between them and the Aurora Borealis? (Both are polar lights.)

The answer in this Flash video by OSUG:

flash video of the northern lights

Watch the video
Published on March 6, 2023
Updated on March 17, 2023