17th century astronomers were the first to refer to the large dark areas on the moon as these

Below you can find the 17th century astronomers were the first to refer to the large dark areas on the moon as these Jeopardy Words Answer. The answer to 17th century astronomers were the first to refer to the large dark areas on the moon as these has 4 letters. This clue belongs to the The moon category and is part of Jeopardy Word Level 28. If you scroll near the bottom you will find other clues and answers part of level 28