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Course: Middle school Earth and space science - NGSS?>?Unit 1
Lesson 1: Earth's place in the universeUnderstand: Earth's place in the universe
Problem
Mars is visible in the night sky from Earth. Most of the time, Mars is seen moving in one direction across the sky. During certain periods, however, the planet seems to move backwards as it travels through the sky.
What type of motion is this an example of?