The Etymologicon: A Circular Stroll through the Hidden Connections of the English Language

Terminators and Equators

If you look up terminator in a dictionary, you’re unlikely to find any reference to death or cyborgs. The first definition will be an astronomical one, because the terminator is the line that divides the illuminated part of a planet from the darker half. So the straight line down the middle of a half-moon is a terminator.

Astronomy and astrology (which were once the same thing) used to be big business until somebody pointed out that huge and distant balls of hydrogen were unlikely to affect your love life. Horoscopes were sent to skulk at the back of the newspaper with the crosswords and personals. Yet the terminology of astrology survives all over the language. For example, if a fellow is of a friendly disposition, it’s because his friendliness is the inevitable consequence of the positions of the planets at the moment of his birth, or rather the distances between the planets, hence disposition.

If Jupiter was in the ascendant when you were born, you are of a jovial disposition; and if you’re not jovial but miserable and saturnine that’s a disaster, because a disaster is a dis-astro, or misplaced planet. Disaster is Latin for ill-starred.

The fault, as Shakespeare put it, is not in our stars; but the language is.

Culmination, opposition, nadir, depression and aspect are all words that we have purloined from the horoscopes and tele­scopes of antiquity. However, astrology is not the only reason that the heavens take precedence over the Earth. There’s the simpler question of visibility. The North Pole, for example, is very far away, and inconveniently located for public transport, but you can see the pole star from your house (providing you’re in the northern hemisphere). The celestial equator is an imaginary projection of the Earth’s equator out into space, and the stars through which this celestial equator passes shine brightly every night no matter where you are, although to reach the real equator requires a journey. And that’s why the word equator referred to part of the sky two centuries before it referred to part of the globe.