Astronomy Practice Exam 2025 – Complete Preparation Guide

The uniqueness of Venus's day in relation to its orbit lies in the fact that its rotation period, or the length of its day, is longer than the time it takes to complete one orbit around the Sun. Venus has a rotation period of about 243 Earth days, making its day significantly longer than its orbital period, which is approximately 225 Earth days.

This phenomenon results in an interesting dynamic for Venus. Despite its longer day, Venus has a retrograde rotation, which means it rotates in the opposite direction to its orbit around the Sun. As a result, when viewed from above the planet's north pole, the Sun appears to rise in the west and set in the east. This combination of slow, retrograde rotation and an orbit that is shorter in duration contributes to the unusual timekeeping on this planet.

In summary, it is Venus's slower rotation compared to its orbital period that makes the length of its day stand out, leading to the conclusion that its day is longer than its orbit around the Sun.