Being the closest planet to the Sun, Mercury has a core made of iron that accounts for ¾ of its diameter, and its size is nearly that of the Moon. The weather on this planet is also extremely harsh, with daytime temperatures soaring to 427 degrees Celsius and nighttime temperatures plummeting to -180 degrees Celsius.
According to image data obtained from the Messenger spacecraft by the National Aeronautics and Space Administration (NASA), Mercury’s diameter has shrunk by more than 13 km over the past 4 billion years. Currently, the diameter of this planet is about 4,800 km, which is 38% of Earth’s diameter. In fact, Mercury is even smaller than Ganymede, Jupiter’s largest moon, and Titan, Saturn’s largest moon.
Mercury is the smallest planet in the Solar System and remains a mystery to humanity.
As the closest planet to the Sun, Mercury is the second hottest planet in the Solar System. The surface temperature facing the Sun can reach 427 degrees Celsius, while the opposite side can drop to -173 degrees Celsius. In comparison, Venus (the second planet from the Sun) has an average temperature of 462 degrees Celsius, making it the hottest planet in the Solar System and holding the record for the most extreme weather in the universe.
Mercury has a lower average density than Earth. It is the second densest planet in the Solar System (5.427 g/cm3), following Earth (5.515 g/cm3), despite its small size. This is because Mercury’s core makes up about 42% of its volume and contains more iron than the other planets.
Mercury and Venus are the only two planets in the Solar System that do not have natural satellites (also known as moons, which are natural objects that orbit a planet or asteroid). With an extremely thin atmosphere, Mercury does not experience seasonal weather changes.
Mercury’s core occupies 42% of its volume and contains a significant amount of iron, which is why its average density ranks just after Earth’s.
Mercury takes only 88 days to complete its orbital cycle (the time it takes for a planet or moon to return to a fixed position in space), which is much faster than other planets. This rapid motion led to Mercury being named after the Roman god Mercury, who is equivalent to Hermes in Greek mythology, the god of communication and messengers.
Being only about 58 million km from the Sun, Mercury is very difficult to reach. In 1974 and 1975, NASA’s Mariner 10 spacecraft visited Mercury three times and mapped nearly half of the planet’s surface.
On August 3, 2004, the Messenger spacecraft was launched into space and entered Mercury’s orbit on March 17, 2011. It conducted missions to observe and study the historical and geological information of the smallest planet in the Solar System.
Messenger concluded its mission by crashing into Mercury at 3:30 PM on April 30, 2015. After more than 4 years of operation, Messenger provided a wealth of valuable data and over 100,000 images of Mercury. One of the most significant discoveries was the giant ice deposits in the northern polar region, which are not exposed to sunlight.
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Mercury’s iron core is nearly the size of Earth’s Moon and constitutes ¾ of Mercury’s diameter. Scientists believe that in the early days of the Solar System’s formation, iron particles were drawn in by the Sun’s magnetic field. As planets began to form from dust and gas, those closer to the Sun received more iron particles than those farther away. Scientists believe that Mercury accumulated the largest amount of iron particles because it is the closest planet to the Sun in the Solar System. This is why this planet has such a dense metallic core. |
