During the centuries, comets have often been associated to mysteries and inauspicious omens by men scanning the sky. In Wanderers of the Sky, Veronique Ataly and Jean-Pierre Luminet, an astrophysicist, tell how comets have revealed little by little their secrets, until the wide knowledge of them we have today. Wanderers of the Sky retraces more than twenty centuries of history, the authors tell us clearly and concisely curious anecdotes about. We can so learn that, in the 4th century BC, while in the West we looked at these celestial objects with apprehension, in many Chinese documents they paid homage to comets. In ancient Rome, it seems that Nero even killed himself after coming to know of the passage of a comet over Jerusalem in 66 AD. Things begin slowly to change during the Renaissance, thanks to the systematic observations by Brahe, Kepler, Galileo. In 1687, five years after Halley’s observation of a huge comet, Newton proved that the periodic appearance of comets is due to the solar and planetary attractive forces. It is only the beginning of a deeper understanding of these wandering space bolides, that, in the 20th century, are still the subject of systematic study.