Final answer:
Mercury experiences extreme temperature fluctuations because it lacks an atmosphere to retain heat; hence, temperatures soar during the day and plummet at night, resulting in a 600 K temperature range.
Step-by-step explanation:
The extreme temperature change on Mercury, despite being the closest planet to the Sun, can be attributed to its lack of a significant atmosphere.
During the day, the temperature on Mercury's surface can reach up to 430 °C due to direct solar heating.
However, at night, the absence of an atmosphere means there is no insulation to retain the heat, causing the temperature to plummet to as low as -170 °C. This results in a temperature range of about 600 K, which is significantly greater than that on any other planet in our solar system.