Names of the Planets
The Latin names of the Planets were simple translations of the Greek names, which in turn were translations of the Babylonian names, which go back to the Sumerians. Some interpretation was required for the Greek, and even for the Babylonian, translations, however. Nergal, for instance, was the god of war but also of pestilence and, especially, the Underworld —overlapping with the Greek Hades. While Kronos was the father of Zeus, Ninurta was the son of Enlil. Ninurta, an obscure god inherited by the Babylonians, may have been identified with Saturn, the slowest moving visible planet, because, at least in one story, he was identified with the turtle. The ancient Egyptian, Sanskrit, and Chinese names for the planets are unrelated to the Sumerian. The Chinese  names for the true planets are derived from the five elements.
I was going through articles I saved to read later this NYT article was form over a year ago! Which, by the way, you should check out as it provides English and Chinese side by side article views. Perfect for improving your reading! Unfortunately, the burden of characters kept me from going into it deeper on Twitter. During my research, I found that there was also a cultural reason for naming Mercury—and the other planets—after elements like water.
Planets in astrology have a meaning different from the modern astronomical understanding of what a planet is. To the Greeks and the other earliest astronomers, this group consisted of the five planets visible to the naked eye and excluded Earth. Although strictly, the term planet applied only to those five objects , the term was latterly broadened, particularly in the Middle Ages , to include the Sun and the Moon sometimes referred to as "Lights"  , making a total of seven planets.