Respuesta :
The thick cloud cover of Venus makes it difficulty in visibility because of impenetrable in visible light which has made it tough for astronomers to measure the length of the planet's day . Whereas Mars have clear atmosphere which do not hinder visibility
The most important reason of why is it difficult to measure the length of the day on Venus is tougher than in mars is that Mars' atmosphere is generally clear because of which their is no visibility issue on mars but due to the thick cloud covering of Venus makes it impenetrable in visible light , due which visibility is not that clear and it become tough to observe the length of the day on Venus.
Mars is much larger than Venus in size which makes easier to observe
To learn more about Mars' atmosphere
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