What competing theory regarding the dark patches on the Sun did Galileo’s initial observations help disprove?

Answer

That they were small, dark planets passing in front of it.

Galileo’s initial observations confirmed that the observed spots were features located directly on the Sun, refuting the competing theory that they were small, dark planets transiting in front of the solar disk.

What competing theory regarding the dark patches on the Sun did Galileo’s initial observations help disprove?
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