David N. Snyder's book says:
"It was believed that Earth was at the center with all of the stars and the Sun revolving around Earth. The prevailing philosophy was this Earth-centered, human-centered idea. If the Earth were bit the center of the universe, it was concluded, then our planet would just be another planet and nothing special in relation to the universe.
Then came the Buddha and in his revolutionary way proclaimed that there are numerous other planets each with its own life forms. He said that these planets are great distances apart from each other (Jayasuriya, 1963) (Majhima Nikaya 3.124) The Buddha said there are "thousands and thousands of suns, thousands of moons, thousands of continents. " Anguttara Nikaya 1.227"
I can't seem to find where these things are said, as much as I google. Any help?