What specific detail about Gan De's ancient sighting of a Jovian companion puzzles modern analysts regarding its reliability?
The description of the object as a "small reddish star."
The challenge to Galileo's priority posed by the ancient Chinese astronomer Gan De, whose records date to approximately 365 BC, revolves around the description of the object seen accompanying Jupiter. Gan De reportedly noted a "small reddish star." This specific coloration description is puzzling to modern analysts because moons are generally too faint for their color to be perceived clearly with the naked eye, especially when viewed alongside the brilliance of the giant planet. Furthermore, this observation lacked the systematic, repeatable nature of Galileo's telescopic campaign, making the ambiguous sighting less scientifically robust than the later photographic or telescopic confirmations.
