Tellurion

Part of speech: noun

Definitions

1. A mechanical apparatus that demonstrates the motions of Earth and the Moon as they orbit the Sun and Earth rotates on its axis
2. An orrery-like device designed to show how Earth spins daily and orbits the Sun while the Moon circles Earth
3. A working model that illustrates Earth's rotation and orbital mechanics along with the Moon's position relative to Earth and Sun

Etymology: A tellurion is a mechanical model that shows how the Earth turns on its axis and moves around the Sun, and it was named by an instrument maker rather than by any ancient scholar. The Oxford English Dictionary records its first known use in 1766, in the work of Benjamin Martin, an English lecturer, lexicographer and maker of scientific instruments, who is also credited with possibly coining the term. The name is built from Latin "tellūs", meaning earth, ground or land, which descends from a Proto-Indo-European root meaning ground or bottom. Martin added "-ion", a Latinate ending chosen in place of the more common "-ian" to form a name for a device. Because English already had "tellurium", the chemical element named after the same Latin root, the two words are related as doublets: separate English forms that came from the same source by different routes.

Synonyms: orrery, planetarium