The planet Mercury derived its name from the Roman god Mercury by virtue of being the fastest planet that travels across the sky. Due to Mercury's proximity to the sun, the planet is able to revolve quickly around the massive heavenly body. The Romans likened and named the planet after their swift-footed god, who is often portrayed in Roman mythology as a lad wearing winged sandals and a winged hat, and holding a caduceus.
Mercury is the smallest of the known planets in the solar system. It completes one revolution around the sun in 88 Earth days. Although it is the closest to the sun, Mercury is not the hottest planet, but rather Venus. During the day, the temperature on Mercury can reach an estimated 800 degrees Fahrenheit, which significantly falls to around -300 degrees at night, due to the planet's extremely thin atmosphere. There are no natural satellites orbiting Mercury.
The earliest historical records regarding the observation of Mercury date back to the ancient Sumerian culture around 3000 B.C. Along with the other four visible planets, namely Mars, Jupiter, Saturn and Venus, Mercury was traditionally called by other names in various civilizations. However, the Roman names were later adopted by Western culture and became standard usage in astronomy.