Which 1613 Galileo work defended the Copernican view while discussing sunspots?

Galileo’s 1613 work Letters on Sunspots defended the Copernican view while discussing sunspots.

The pamphlet, originally titled Istoria e Dimostrazioni intorno alle Macchie Solari, was written as a series of letters and published in Rome by the Accademia dei Lincei. Galileo argued that sunspots were features on or near the Sun’s surface, carried along as the Sun rotated, rather than separate planets or satellites orbiting above it.

The argument challenged the Aristotelian idea that the heavens were perfect, unchanging, and free of blemishes. Galileo also used the work to discuss telescopic observations of Venus’s phases, which provided important evidence that Venus circles the Sun rather than Earth. The work therefore connected a dispute about solar blemishes with the larger Copernican debate.

The controversy involved the Jesuit astronomer Christoph Scheiner, who initially proposed that sunspots might be bodies passing in front of the Sun. Galileo’s letters became increasingly polemical, and the dispute later continued in The Assayer. A frequent mix-up is with Starry Messenger, Galileo’s 1610 work about the Moon, stars, and Jupiter’s satellites; that earlier book did not bear this sunspot title.