Et si le SOLEIL s'éteignait maintenant ?

The video explores the question of what would happen if the Sun were to suddenly stop shining. It begins by referencing science fiction films like Sunshine and Project Hail Mary, which depict the Sun dimming, and clarifies that such scenarios are fictional. The creator explains that the Sun is a plasma ball powered by nuclear fusion in its core, converting hydrogen into helium and losing mass in the process. The Sun is in a delicate equilibrium between gravity and radiation pressure, with a stable 11-year cycle and minimal luminosity variation. The video discusses the Sun’s future evolution: it will gradually brighten, leading to the evaporation of oceans in about 500 million years and the end of all carbon-based life in a billion years. In about 5 billion years, the Sun will become a red giant, engulfing Mercury and Venus, and eventually leave behind a white dwarf. The hypothetical scenario of instantly stopping fusion is then considered: the Sun would not immediately go dark because photons take between 100,000 and 170,000 years to travel from the core to the surface. The Sun would slowly contract over 20 million years, giving humanity ample time to prepare for interstellar travel. The video concludes that the Sun cannot suddenly extinguish, and even in a magical scenario, we would have 100,000 years of light reserve.