Propus

Its story

Propus, in the constellation of Gemini, is a variable red giant 385 light-years from the Earth, one of the more capricious stars of the winter sky in the northern hemisphere. Its name, taken directly from ancient Greek, means «the foot set forward»: it marks with quiet symbolic precision the stride of one of the two celestial twins in their endless joint march. Its light fluctuates slowly, and until a few decades ago it was one of the stars that amateur astronomers patiently watched, with exemplary care, for the smallest shifts in brightness from the balcony at home.