Present tense for general truths

General truths or scientific principles should appear in the present tense, unless such principles have been disproved.

Example sentence with editing. Original sentence: Galileo taught that the earth revolved around the sun. Revised sentence: Galileo taught that the earth revolves around the sun. Explanation: The past-tense verb 'revolved' has been replaced by the present-tense 'revolves.'

Since Galileo’s teaching has not been discredited, the verb should be in the present tense. In the following sentence, however, the past-tense verb is acceptable:

Example sentence: Ptolemy taught that the sun revolved around the earth.