What planet is the slowest rotating and often referred to as Earth’s “sister planet?”
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A
Mercury
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B
Venus
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C
Venus
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D
Mars
Venus is often referred to as Earth’s “sister planet,” and it has the slowest rotation of any planet in the solar system.
- A) Mercury:
- Mercury has a very short day compared to other planets, with one full rotation taking only about 59 Earth days. However, it does not rotate as slowly as Venus. While it is often discussed in terms of its proximity to the Sun and lack of an atmosphere, it is not Earth’s “sister planet” nor the slowest rotating planet.
- B) Venus:
- Venus is often referred to as Earth’s “sister planet” due to its similar size and composition. However, it is also known for having the slowest rotation of any planet in the solar system. Venus takes about 243 Earth days to complete one rotation, which is slower than its orbit around the Sun (which takes about 225 Earth days). This means a day on Venus is longer than its year. It is a unique feature of Venus, making B) Venus the correct answer.
- C) Jupiter:
- Jupiter has a very fast rotation, completing one rotation in about 10 hours. It is the largest planet in the solar system but is not the slowest rotating. Its fast rotation is responsible for its oblate shape (flattened at the poles).
- D) Mars:
- Mars has a rotation period very similar to that of Earth, taking 24.6 hours to complete one rotation. While it is often referred to as Earth’s “twin” in terms of its day length and surface conditions, it does not have the slowest rotation.
Conclusion: The planet with the slowest rotation and often referred to as Earth’s “sister planet” is Venus, making B) Venus the correct answer.
Topic Flashcards
Click to FlipWhat is the approximate length of one rotation (a sidereal day) on Venus in Earth days?
About 243 Earth days.
Venus is often called Earth's "sister planet." What two key physical characteristics are very similar between them?
Similar size and mass (also similar composition/density).
Venus's rotation is not only slow but also in the opposite direction of most planets. What is this type of rotation called?
Retrograde rotation.
On Venus, which is longer: its day (one rotation) or its year (one orbit around the Sun)?
Its day (243 Earth days vs. 225 Earth days for its year).
What is the primary reason Venus, not Mars or Mercury, is most often called Earth's "sister" or "twin"?
It is the planet closest to Earth in terms of overall size, mass, gravity, and bulk composition.