This seems too easy but "In the beginning God created the heavens (plural) and the earth (singular)"
But isn't it just possible that God did not reveal to us absolutely everything that He did in the Bible. It doesn't say in the Bible that He did or He did not create other planets. The singular usage for earth doesn't prove He didn't. Maybe He gave a different name to the other planet(s) that He created. We just don't know at this point. For either religious people or scientists to suggest that we do know is ridiculous.
This has made a lot of people very angry and been widely regarded as a bad move.