Final answer:
It is true that the exact cause of Venus's slow retrograde rotation remains unknown. Venus's rotation is longer than its year, and the planet exhibits environmental conditions vastly different from Earth, despite sharing some similarities in mass and density.
Step-by-step explanation:
The statement that 'The cause of Venus's slow rotation is unknown at present' is True. Venus exhibits a very slow retrograde rotation, taking 243 Earth days to complete one spin on its axis, which is longer than its orbital period of 225 Earth days around the Sun. Consequently, a day on Venus, as defined by one rotation, is longer than a Venusian year. The phenomenon of a slow, backward rotation is unusual and while hypotheses suggest it may be due to powerful collisions during the solar system's formation, the exact reason remains unclear.
Understanding the rotation periods of planets, such as Venus's peculiar retrograde motion, aids in a deeper comprehension of the solar system's dynamics and history. Venus's rotation can only be studied using radar due to its dense cloud cover, which obscures any surface details from visual telescopes. This technique established that Venus spins in a direction opposite to most planets in the solar system. Despite the planet's similarities to Earth in terms of mass and density, the environmental conditions on Venus are drastically different, indicated by its extreme atmospheric pressure and scorching surface temperatures. These details underscore the complexity and diversity of planetary formation and evolution processes. The ongoing study of Venus’s rotation period and direction continues to be a profound puzzle in planetary science.