This is the closest planet to the Solar System, with a diameter just over one-third that of Earth.
Questions
Question 1: Which is the smallest planet in the Solar System?
a. Mercury
b. Saturn
c. Uranus
Question 2: Mercury is the hottest planet in the Solar System, true or false?
a. True
b. False
Question 3: Which of the following does not correctly describe Mercury?
a. Mercury has the highest average density in the Solar System
b. Mercury has no natural satellites
c. Mercury does not have seasonal weather changes
Question 4: How many Earth days does it take Mercury to complete its orbital cycle?
a. 68 days
b. 78 days
c. 88 days
Question 5: How many spacecraft have approached Mercury?
a. 2
b. 1
c. 0
Answers
Question 1: a – Mercury. Mercury is the closest and smallest planet in the Solar System. According to image data obtained from NASA’s Messenger spacecraft, 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, the largest moon of Jupiter, and Titan, the largest moon of Saturn.
Question 2: b – False. Despite being closest to the Sun, Mercury is the second hottest planet in the Solar System. The surface temperature facing the Sun can reach up to 427 degrees Celsius, while the opposite side can drop to -173 degrees Celsius. Meanwhile, 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.
Question 3: a – Mercury has a lower average density than Earth. Mercury is the second densest planet in the Solar System (5.427 g/cm3), after 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 other planets. Mercury and Venus are the two planets in the Solar System without natural satellites (also known as moons, which are natural objects orbiting a planet or asteroid). With its extremely thin atmosphere, Mercury does not experience seasonal weather changes.
The core of Mercury (right) makes up 42% of its volume and contains a lot of iron, making its average density second only to Earth (left). (Photo: Steemit)
Question 4: c – 88 days. Mercury takes only 88 days to complete its orbital cycle (the time it takes for a planet or satellite to return to a fixed position in space), which is much faster than other planets. This rapid movement led to Mercury being named after the Roman god Mercury, who is equivalent to Hermes, the messenger god in Greek mythology.
Question 5: a – 2. Due to being only about 58 million km from the Sun, Mercury is very difficult to approach. In 1974 and 1975, NASA’s Mariner 10 visited Mercury three times and mapped less than half of the planet’s surface. On August 3, 2004, the Messenger spacecraft was launched into space and entered orbit around Mercury on March 17, 2011. It conducted a mission 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 valuable data and over 100,000 images of Mercury. One of the greatest discoveries was a massive ice deposit in the northern polar region, an area not exposed to sunlight.
