Only 6,000 are visible to the naked eye, but their actual number is astronomical. Stars enchant our nights and seem to shine immutably, serving as reliable landmarks for travelers and inspiration for poets since the dawn of time. Yet behind this nocturnal enchantment lies a relentless struggle against gravity, which pushes stars into extreme conditions. We will discover how these stars participate in the great cycle of matter and how atoms produced in the furnace of their cores can end up on a small, hospitable planet and enable the emergence of life. Lecture by Sylvia Ekström, associate professor in the Department of Astronomy at UNIGE. The evening will continue with sky observation, weather permitting.