Now it is quite clear to me that there are no solid spheres in the heavens, and those that have been devised by the authors to save the appearances, exist only in the imagination.
Meaning of the quote
Tycho Brahe, a famous Danish scientist, believed that the idea of solid spheres in the heavens was just an imagination made up by other authors to explain what they saw in the sky. He realized that these solid spheres did not actually exist and were not real.

About Tycho Brahe
Tycho Brahe was a renowned Danish astronomer of the Renaissance, known for his highly accurate astronomical observations. He made groundbreaking discoveries, including observing a supernova and showing that comets were not atmospheric phenomena. Tycho Brahe’s research program helped transform astronomy into a modern science and contributed to the Scientific Revolution.
More quotes from Tycho Brahe
I conclude, therefore, that this star is not some kind of comet or a fiery meteor… but that it is a star shining in the firmament itself one that has never previously been seen before our time, in any age since the beginning of the world.
Danish astronomer and alchemist, 1546-1601
Now it is quite clear to me that there are no solid spheres in the heavens, and those that have been devised by the authors to save the appearances, exist only in the imagination.
Danish astronomer and alchemist, 1546-1601
It was not just the Church that resisted the heliocentrism of Copernicus.
Danish astronomer and alchemist, 1546-1601
When, according to habit, I was contemplating the stars in a clear sky, I noticed a new and unusual star, surpassing the other stars in brilliancy. There had never before been any star in that place in the sky.
Danish astronomer and alchemist, 1546-1601
With a firm and steadfast mind one should hold under all conditions, that everywhere the earth is below and the sky above, and to the energetic man, every region is his fatherland.
Danish astronomer and alchemist, 1546-1601