A flat projection of the night sky, an astrolabe was used to help calculate the positions of the stars and to determine the exact time during the day. Mentioned by several ancient Greek authors, this measuring and navigational instrument was used up to the 18th century, when it was replaced by more sophisticated optical instruments. Combining the scientific knowledge of the East and West, this finely engraved astrolabe stands out due to its size, exceptional for this type of artefact.