Problem 1: During which months do Mars appear to be moving backward in its orbit?
Problem 2: Carefully observe what is happening to Earth and Mars in their orbits when Mars seems to loop "backward". What causes Mars to seem to move backward in its orbit?
Problem 3: Consider the order of the planets in our solar system (closest to the sun outward): Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Looking from Earth, which other planets would be seen in retrograde? (Assume all planets can be seen with the naked eye)
Problem 4: If we could view the planets from Mercury, which planets could be retrograde?
Problem 5: What has to be true about a planet's orbit in order to see it in retrograde?
Problem 6: Would Jupiter's retrograde "loop" be bigger or smaller than the Mars's retrograde loop? Explain why.
Problem 7: If you were observing the sky for several months, which would move more planets or stars? Explain why.
Problem 8: How could you tell a planet from a star in the night sky?