The Northern lights

The auroras were even observed in the skies over Paris, despite the high levels of light pollution.                                                                                                                                                                  Credit: LeMonde

How can we explain such auroras far from the North Pole? (Auroras in the Southern Hemisphere are called auroras australis).
Storms of this intensity only occur 1 or 2 times during peak solar activity, meaning every 11 years: the last similar solar storm was in 2003. In fact, the sun seems to follow an 11-year cycle that astronomers have observed over the years. Every 11 years, it enters a phase of high activity, when it is possible to observe large-scale brown spots on the surface of our star with a proper telescope.

 Credit: Futura-Sciences

These spots are evidence of high activity: the star forms giant plasma loops and ejects large quantities of plasma.                                                                                                                                                ​​​Credit: Wikipédia

During these eruptions, it sends thousands of solar particles in the same direction. When these eruptions occur on the same trajectory as the one between the star and the Earth, the particles are sent directly to meet our planet. When they reach us, they collide with our magnetic field, which is designed to protect us from them, but is nevertheless weak at the poles.

                                   Credit: La Dépêche

Some of the solar particles then manage to slip through the 2 openings, and come into contact with our atmosphere. It's easy to see that the more powerful the solar flare, the greater the quantity of solar particles emitted, and the more auroras will be visible far from the poles.
Yet it is precisely the collision between the particles that compose our atmosphere, such as oxygen, and the highly-charged solar particles that produces the colors so characteristic of the aurora borealis.

                                                                      Credit: Culture Sciences Physique

Some auroras are pink/red, like those observed in the Northern Hemisphere on the night of May 10/11: this color means that the solar particles are reacting with the oxygen present in the upper atmosphere, some 300km away. On the other hand, when they are green, this means that they are reacting with oxygen in the lower atmosphere.