Astronomy Practice Exam 2025 – All-in-One Guide to Master Your Astronomy Test!

The primary reason for Venus's unusual rotation direction is indeed that it may have been impacted by a large object. Venus rotates on its axis in the opposite direction to most planets in the solar system, which is referred to as retrograde rotation. This peculiar rotation could be the result of a significant collision with a large celestial body during its formation, which might have altered its rotational dynamics.

This impact hypothesis is supported by the fact that many other bodies in the solar system, including Venus’s own lack of significant moons, point towards a history of collisional events. The nature of these impacts can drastically affect a planet's rotation, leading to the unique circumstances observed with Venus today. Other options, such as having high gravity, being the coldest planet, or having many moons, do not directly relate to the reasons behind its rotation direction. In fact, Venus has no natural satellites, which distinguishes its rotation even further among the inner planets.