Section 1 Earth er Support & Planning 1. Properties of Earth people used to think that Earth was flat and at the center of the universe. Underlined words and phrases are to be filled in by students on the Note-taking Worksheet. 1. Earth is now known to be a round, three-dimensional sphere. a Axis-imaginary vertical line around which Earth spins b. Rotation the spinning of Earth around its axis that causes day and night 2. Earth has a magnetic field with north and south poles. 3) Magnetic axis-imaginary line joining Earth's magnetic noli