📚 Part of: Bangladesh Independence & South Asian History Mcqs

Which planet in our solar system takes the longest time to complete its revolution around the sun.

Category: Miscellaneous Indian Gk

Correct Answer: D) Neptune.

Exam Relevance: UPSC, GRE, GMAT, SAT, Astronomy Exams

Difficulty: Moderate

Concept notes:

The time taken by a planet to complete one full revolution around the sun is known as its orbital period or year. The orbital period varies for each planet due to their different distances from the sun and their varying speeds. Neptune, being the farthest planet from the sun, has the longest orbital period.

Common Mistakes:
  • Confusing the size of the planet with the length of its orbital period.
  • Assuming that the planet with the largest mass has the longest orbital period.
  • Not understanding that the distance from the sun significantly affects the orbital period.
Explanation:

In the solar system, the time taken by a planet to complete one full revolution around the sun is known as its orbital period or year. The orbital period of a planet is determined by its distance from the sun and its speed. According to Kepler's laws of planetary motion, the farther a planet is from the sun, the longer its orbital period. This is because the gravitational force exerted by the sun on a planet decreases with the square of the distance from the sun. As a result, planets farther from the sun move more slowly in their orbits, leading to longer orbital periods.

The planets in our solar system, in order of their distance from the sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Among these, Neptune is the farthest from the sun, and thus it has the longest orbital period. Neptune takes approximately 164.79 Earth years to complete one orbit around the sun. This is significantly longer than the orbital periods of the other planets, such as Jupiter (11.86 Earth years), Saturn (29.46 Earth years), and Uranus (84.01 Earth years).

Understanding the orbital periods of the planets is crucial for comprehending the dynamics of the solar system. It helps in predicting the positions of planets, understanding their relative speeds, and studying their interactions with other celestial bodies. The orbital period of a planet is a fundamental concept in astronomy and is essential for various applications, including space missions and the study of exoplanets.

In summary, Neptune has the longest orbital period among the planets in our solar system due to its great distance from the sun. This concept is important for understanding the structure and dynamics of the solar system and is a key topic in astronomy and related fields.

Option Analysis:
  • Option A: Jupiter is incorrect. Jupiter is the fifth planet from the sun and has a shorter orbital period than Neptune. Jupiter takes about 11.86 Earth years to complete one orbit around the sun. The misconception here might be that Jupiter, being the largest planet, would have the longest orbital period, but size does not determine the length of the orbital period.
  • Option B: Earth is incorrect. Earth takes one Earth year to complete one orbit around the sun. This is a common misconception because Earth is the planet we are most familiar with, and it might be assumed that it has the longest orbital period. However, Earth is relatively close to the sun and thus has a shorter orbital period compared to the outer planets.
  • Option C: Saturn is incorrect. Saturn is the sixth planet from the sun and has a longer orbital period than Earth but shorter than Neptune. Saturn takes about 29.46 Earth years to complete one orbit around the sun. The misconception here might be that Saturn, being a gas giant and farther from the sun than Earth, would have the longest orbital period, but Neptune is farther out.
  • Option D: Neptune is correct. Neptune is the eighth and farthest planet from the sun, and it takes about 164.79 Earth years to complete one orbit around the sun. This is the longest orbital period among all the planets in our solar system. The misconception might be that the largest planet (Jupiter) or the gas giants (Saturn) would have the longest orbital period, but the distance from the sun is the key factor in determining the length of the orbital period.
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