Night envelops the Semnoz site above Lake Annecy in mid-January. The recently fallen snow offers snowshoe hikers a beautiful walk among the fir trees, which they illuminate with their headlamps. In the valley, the sea of clouds covers the lights of the lakeside villages, until the Col de Bluffy comes into view on the left. In the middle of the valley, the Tournette massif struggles to hide the dazzling activity of the La Clusaz ski resort's snow groomers, and Mont-Blanc looks a long way off, 80 km away on the horizon. In the sky, the winter Milky Way reveals on its right the constellation of Orion and its emblematic nebula, while Sirius, the brightest star in the celestial vault, has just risen above the horizon.