Galileo recorded 36 stars in his drawing of the Pleiades cluster in Sidereus Nuncius. His telescope transformed the familiar naked-eye star group into a much richer celestial scene.
To observers without optical aid, the Pleiades—also called the Seven Sisters—typically showed six clearly visible stars to Galileo, with a seventh difficult to see. Through his improved telescope, he detected many fainter stars packed around them. In the text accompanying his illustration, Galileo noted that more than forty additional stars lay near the bright group, while his diagram specifically included thirty-six of those telescopically visible stars.
The observation appeared in Sidereus Nuncius, published in Venice on March 13, 1610. The work was among the first major scientific publications based on telescopic observations and also included drawings of the Moon, Orion, the Milky Way, and Jupiter’s satellites. A common mix-up is between the number of stars Galileo drew and the number visible to the naked eye: “seven” refers to the traditional name of the cluster, not to the total number he recorded. Some modern summaries describe the drawing as showing thirty-five stars because of counting conventions, but the original passage and the quiz’s canonical figure give 36.