Question

Order the answers to complete this description of Mercury's orbit around the Sun. "Mercury is the _____ planet to the Sun and in accordance with Kepler's third law, it has the _____ period of revolution about the Sun and the _____ average orbital speed. As you might expect, it's best seen when its eccentric orbit takes it as _____ from the Sun as possible. The semimajor axis of Mercury's orbit is _____ kilometers, or _____ AU. However, because its orbit has the high eccentricity of _____, Mercury's actual distance from the Sun varies from _____ kilometers at perihelion to _____ kilometers at aphelion."

Answer 1

Mercury is the closest planet to the Sun, and by Kepler's third law, it has the shortest period of revolution about the Sun and the highest average orbital speed. As you might expect, it's best seen when its eccentric orbit takes it as far from the Sun as possible. The semimajor axis of Mercury's orbit is 57,909 kilometers or 0.387 AU. However, because its orbit has a high eccentricity of 0.206, Mercury's actual distance from the Sun varies from 46 million kilometers at perihelion to 70 million kilometers** at aphelion.

Step-by-step explanation:

Mercury's designation as the closest planet to the Sun is a result of its small semimajor axis, which is the average distance from the Sun. Calculated at 57,909 kilometers, or 0.387 AU, this value is fundamental to understanding its proximity to the Sun compared to other planets. Kepler's third law of planetary motion states that the square of the orbital period of a planet is directly proportional to the cube of the semimajor axis of its orbit.

Given Mercury's short semimajor axis, it follows that it has the shortest period of revolution around the Sun and the highest average orbital speed.

The eccentricity of Mercury's orbit, which measures how much the orbit deviates from a perfect circle, is 0.206. This high eccentricity accounts for the significant variation in Mercury's distance from the Sun. At its closest point or perihelion, Mercury is a mere 46 million kilometers from the Sun, while at its farthest point, or aphelion, it is 70 million kilometers away. This orbital eccentricity contributes to the observed phenomenon that Mercury is best visible when it reaches its maximum distance from the Sun, enhancing its visibility in the night sky.

Answer 2

Mercury is the closest planet to the Sun, and in accordance with Kepler's third law, it has the shortest period of revolution about the Sun and the highest average orbital speed. As you might expect, it's best seen when its eccentric orbit takes it as far from the Sun as possible. The semimajor axis of Mercury's orbit is 57.91 million kilometers, or 0.39 AU. However, because its orbit has the high eccentricity of 0.21, Mercury's actual distance from the Sun varies from 46 million kilometers at perihelion to 69.8 million kilometers at aphelion.

Step-by-step explanation:

Mercury, the closest planet to the Sun, exhibits unique characteristics in its orbit. According to Kepler's third law, which relates the orbital period of a planet to its distance from the Sun, Mercury has the shortest period of revolution and the highest average orbital speed among all planets. This proximity to the Sun also influences its visibility, with Mercury being best observed when its eccentric orbit takes it as far from the Sun as possible.

The semimajor axis of Mercury's orbit, measuring 57.91 million kilometers or 0.39 astronomical units (AU), provides a crucial parameter describing its average distance from the Sun. However, the orbit's high eccentricity of 0.21 introduces significant variability in Mercury's actual distance from the Sun. At perihelion, the closest point to the Sun, Mercury is approximately 46 million kilometers away, while at aphelion, the farthest point, it extends to around 69.8 million kilometers.