Astronomy Practice Exam

Which planet's orbit results in it experiencing retrograde rotation?

1. Earth

2. Mars

3. Venus

4. Jupiter

The correct answer is: Venus

The correct answer is the planet Venus, which experiences retrograde rotation. Retrograde rotation refers to a rotational movement opposite to the direction of the orbit around the Sun. In the case of Venus, it rotates on its axis in a direction opposite to its orbit; that is, it rotates clockwise when viewed from above its north pole, whereas most of the planets, including Earth, rotate counterclockwise. This unusual rotation of Venus results in a uniquely long day, as it takes approximately 243 Earth days to complete one rotation, which is longer than its year of about 225 Earth days. The phenomenon is believed to be a result of significant collisions with other celestial bodies during its formation, leading to a change in its rotation path. The other planets, including Earth, Mars, and Jupiter, all have prograde rotation, meaning they rotate in the same direction as they orbit the Sun. Therefore, among the options provided, Venus stands out as the only planet that exhibits retrograde rotation.