Did Christoph Scheiner ever come around to the Copernican model or accept that sunspots were a phenomenon that occurred on the surface of the sun?
The Parallel Worlds of Christoph Scheiner and Galileo Galilei
Galileo Galilei and Christoph Scheiner, working independently, discovered many of the properties of sunspots that we accept as valid today. Using his precise drawings of sunspots, Scheiner discovered seasonal variations in the slope of sunspot tracks. These led him to measure a small inclination of the solar axis with respect to the ecliptic plane. Galileo interpreted the variations of sunspot tracks as strong evidence in support of the Copernican model of the planets and Sun. Scheiner, in contrast, sought to reconcile his discoveries with his belief in Church dogma. He rejected the Copernican model and adopted instead Tycho Brahe’s hybrid geocentric model, which was consistent with all pertinent observations.
The reason I ask is that some websites state that Scheiner initially argued that the sunspots were satellites and not a sun surface phenomenon. But what I have not come across is any commentary on any change in Scheiner’s position.
This page in the Galileo Project, published by Rice University, says that Scheiner did initially argue that sunspots were solar satellites, but later changed his mind:
Scheiner had in the meantime published several important books on optics, and he had continued his study of the Sun. He published his results in a massive tome, Rosa Ursina , (“The Rose of Orsini”), which became the standard treatise on sunspots for over a century. Scheiner had abandoned his opinion that spots were solar satellites, and he indeed came out in favor of the system of Tycho Brahe and abandoned the perfection of the heavens.
Tycho’s model, meanwhile, had the Earth at the center of the Universe, the Sun (and Moon) going around the Earth, and then everything else going around the Sun. It makes exactly the same predictions as the purely-heliocentric model, and in principle can’t be distinguished from it even today. It’s a matter of personal judgement whether the supposed doctrinal benefits are worth the increase in complication (though most persons nowadays make the judgement that it isn’t worth it).
Stellar abberation it explained by the Copernican heliocentric but not the Tycho geoheliocentic system.
As early as 1573, Thomas Digges had suggested that parallactic shifting of the stars should occur according to the heliocentric model, and consequently if stellar parallax could be observed it would help confirm this theory. Many observers claimed to have determined such parallaxes, but Tycho Brahe and Giovanni Battista Riccioli concluded that they existed only in the minds of the observers, and were due to instrumental and personal errors. However, in 1680 Jean Picard, in his Voyage d’Uranibourg, stated, as a result of ten years’ observations, that Polaris, the Pole Star, exhibited variations in its position amounting to 40″ annually. Some astronomers endeavoured to explain this by parallax, but these attempts failed because the motion differed from that which parallax would produce.
No, even that, you can make work. Once relativity gets involved (as it does with stellar aberration), it gets far, far more complicated, but you can still do it. Or rather, in another sense, it’s not complicated at all: The easy way to do all of the necessary calculations is to just switch back to the sane reference frame, and all you need to do to make the change back to the Earth frame is to declare by fiat “the Earth is at rest”.
Here’s a discussion of Schnieder’s observations of sunspots… https://iopscience.iop.org/article/10.3847/1538-4357/ac52ee#:~:text=Because%20of%20the%20Aristotelian%20ideas,celestial%20bodies%20orbiting%20the%20Sun. It does mention what really changed Schnieder’s mind… he observed the sunspots paths are different because of the latitude of the sunspot… The ones at the top move a short distance slowly, the ones across the equator move the largest distance, and in the same period, ie faster speed. But all the paths are parallel …so he realised the axis of the sun is perpendicular to the paths of the sunspot…
But presumably the confusing part was admitting that the sun’s “surface” rotated at different speeds, hence the sunspots at different latitudes traversing different speeds. Unless they could conceive of a fluid globe, a bit of a second incredible leap in those days, or migrating surface phenomenon, the motion made no sense as a surface phenomenon.
Galileo’s reasonable-but-incorrect interpretation was that they were clouds. Even if one assumes that the body of the Sun is solid, it’s no great leap to suppose that it might have an atmosphere, nor would it have seemed odd that a body with an atmosphere might have different prevailing winds at different latitudes.