Which two motions are the main motions of the Earth discussed in this material?

• A. Rotation and Tilt
• B. Rotation and Revolution
• C. Revolution and Orbit
• D. Tilt and Spin

Answer: (B)

Earth’s two fundamental motions are rotation and revolution. Rotation is the planet spinning on its axis, which creates day and night as different parts of Earth face the Sun in a roughly 24-hour cycle. Revolution is its movement around the Sun, taking about a year to complete an orbit. Tilt affects how sunlight falls on the Earth and drives seasons, but it’s a tilt rather than a motion. Orbit refers to the path around the Sun, while revolution is the motion along that path. Spin is another word for rotation, but the standard terms used here are rotation and revolution. So, rotation and revolution best describe Earth's main motions.