The ancient Greeks were very well known for the many discoveries and inventions that they made in the field of astronomy. They questioned the way that the universe worked and dug deeper into what existed in the skies. This allowed them to find new things that had never been seen before and discover things that had never been heard of. People like Hipparchus and Ptolemy extensively studied the stars and the planets, and so they, along with several other Greeks, were able to learn about revolutionary concepts that the rest of the world had never even thought of. The size of the Sun, Moon, and Earth and the distances between them, the length of a year, and the ways that the planets move are among just a few of the things that have been discovered by Greek astronomers. What the ancient Greeks observed thousands of years ago is used today to help inspire and influence new astronomical discoveries.