Our Place in the Universe

Since the beginning of human civilization, people have wondered about the structure of the cosmos and our place in the Universe.  More than 2,000 years ago, our ancestors knew that the seasons were unequal, the Earth was an unattached object floating in space, and stars existed that they could not see.  From celestial observations, they concluded that the Earth was round.  Using simple tools and mathematics, ancient astronomers accurately determined the sizes of the Earth and Moon, the distance to the Moon, and the lengths of the months and year.