Who named planet 'Earth'? Tracing the origins of our planet's name

Among the planets in our solar system, Earth stands out not just for its life-supporting capabilities but also for its unique name. Unlike its celestial neighbors—Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune—all of which were named after Greek or Roman gods, Earth derives its name from more humble linguistic roots. The etymology of the word 'Earth' reflects a fascinating tapestry of ancient languages and cultural evolution. But who exactly coined the name, and how did it come to refer to our planet as a whole? Delving into history, mythology, and linguistics, this article uncovers the intriguing story behind the name "Earth."

In antiquity, Greek and Roman mythology heavily influenced the naming of celestial bodies. Jupiter, the chief Roman deity, and Mars, the god of war, lent their names to planets that reflected their characteristics in the night sky. Similarly, the Greek goddess Gaia, known as the personification of Earth, and her Roman counterpart Terra Mater symbolized the nurturing and life-giving aspects of the ground beneath our feet. While mythology played a significant role in naming other planets, Earth's name evolved from more practical and linguistic origins rather than being attributed to a specific deity.

The term "Earth" has its origins in the Old English word eorþe, which encompassed meanings such as "soil," "ground," "dry land," and "country." Old English, the earliest phase of the English language (used from roughly 450 CE to 1150 CE), itself descended from Proto-Germanic, a reconstructed ancient language that gave rise to many modern Germanic tongues.

The linguistic relatives of "Earth" can be traced across several languages:

Linguists have reconstructed a Proto-Germanic root word, ertho, to account for these similarities, even though no direct written records of this term exist. Its widespread use likely reflected early people's direct relationship with the land, emphasizing the physical ground rather than the celestial body.

The precise moment when words like eorþe or Erde began to denote the entire planet rather than just the ground is uncertain. Unlike modern times, ancient civilizations often lacked the concept of Earth as a spherical planet among others in the solar system. Instead, their understanding revolved around their immediate surroundings.
In scientific circles, the planetary identity of Earth became more prominent after the Copernican Revolution in the 16th century, when heliocentrism placed Earth as one of several planets orbiting the Sun. However, the linguistic shift to using "Earth" as a proper noun for the planet likely occurred gradually and informally over centuries.

In contrast to Earth, the other planets were explicitly named by ancient civilizations based on observable characteristics and mythological significance. For example:

Even more recent discoveries like Uranus and Neptune followed this tradition, named after Greek gods representing the sky and the sea, respectively.

Earth’s name reflects a grounded and pragmatic perspective, emphasizing its role as "the ground beneath us" rather than its place among celestial entities. This distinction underscores humanity's ancient focus on survival, agriculture, and connection to the land rather than an early understanding of planetary science.

In contemporary English, the capitalisation of "Earth" depends on its usage. According to the University of Oxford Style Guide, when referring to the planet itself, "Earth" should be capitalized (e.g., "The astronauts returned to Earth"). However, when discussing soil or ground in a general sense, it remains lowercase (e.g., "They dug into the earth"). This nuanced usage reflects both the linguistic and scientific evolution of the term.