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A Planet of Extremes 

Mercury’s orbit is a swift and eccentric journey, completing a full revolution around the Sun in just 88 days. Racing through space at an astonishing speed of 112,000 km/h, Mercury claims the title of the fastest planet in our celestial neighborhood. Its path, however, is far from simple; the planet boasts the most elongated orbit among its peers. The distance from the Sun varies dramatically, spanning from 29 million to 43 million miles (46 million to 69 million km).

Intriguingly, Mercury’s small diameter of 4880 km marks it as the solar system’s smallest planet, and it’s shrinking further due to the cooling of its iron core. This unique feature results in a remarkable phenomenon—Mercury’s surface is marred by a single, sprawling continental plate, giving rise to colossal rock formations and valleys shaped by compression.

Temperature fluctuations on Mercury are nothing short of astonishing, swinging between scorching highs of +427°C (800.60°F) during the day and chilling lows of -170°C (-274°F) at night. Moreover, the planet’s atmosphere is nearly nonexistent, with a concentration of gases at its surface several orders of magnitude lower than the orbit of the International Space Station.

Mercury’s elongated orbit and prolonged day combine to create a breathtaking spectacle exclusive to its surface. During perihelion, the planet’s orbital speed surpasses its rotation, causing the Sun to momentarily halt and then backtrack in the sky—a unique dance where our luminary appears to rise, set, and rise again. This performance is called the “Joshua Effect” after the biblical story of the hero stopping the sun.

Exploring Mercury has been a formidable challenge for spacefarers. The MESSENGER spacecraft embarked on a 6.5-year odyssey, involving six gravitational maneuvers and covering an astonishing 7.9 billion km—greater than the distance between Earth and Pluto—to enter its orbit. Only three earthly emissaries have visited this captivating planet: Mariner 10 conducted three flybys in 1974-1975, MESSENGER orbited from 2011 to 2015, and the BepiColombo mission, launched in 2018, made its first flyby on October 1, 2021, continuing our quest to unlock the secrets of Mercury’s mysteries.

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