Which planet has the longest day?

Question: Which planet has the longest day?

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The planet in our solar system with the longest day, defined as one complete rotation on its axis, is Venus. Despite being only the second planet from the sun, Venus has an extremely slow rotational speed.

Venus completes a rotation on its axis roughly every 243 Earth days, making its day longer than its year, which lasts approximately 225 Earth days. This unusual circumstance makes Venus unique among the planets in our solar system. It’s also interesting to note that Venus rotates in the opposite direction to most other planets, including Earth, a phenomenon known as retrograde rotation.

However, due to its orbital motion and retrograde rotation, Venus’s solar day – the time it takes for the sun to return to the same place in the sky – is about 116.75 Earth days. This is the period that would most closely resemble our concept of a day.

Venus’s long day has impacts on its climate, contributing to its incredibly high surface temperatures. The slow rotation limits the redistribution of heat from the day side to the night side, contributing to Venus being the hottest planet in our solar system.