© www.astrostudio.at / Gerald Rhemann
The night sky was really important to ancient people. This can be hard for us to understand, living as we do in a world where light pollution denies us a clear view of the stars. What people saw in the sky - or thought they saw - they expressed as myths, as symbols, and even as designs on their coins. The crescent moon and spiky stars, for example, appear frequently on ancient coins.
Most ancient cultures believed in astrology - the notion that changes observed in the heavens above were strongly linked to events on earth below. Along with the reassuringly predictable motions of the stars and planets, more troubling things sometimes appeared in the sky.
Rare and unpredictable, comets and meteors were particularly potent symbols, and their appearance on a few ancient coins has sparked the interest of historians and astronomers as well as numismatists.
We know now that comets are large "dirty snowballs" with eccentric orbits that sometimes bring them close enough to the sun that long tails of gas and dust reflect enough sunlight to make them visible. The Greek word kometes means "long-haired." One Latin term for comet was stella crinita
- "hairy star."
Aristotle thought comets were the result of combustible gas igniting in the upper atmosphere. Some ancients believed they were wandering planets. But many believed they were omens of natural or political catastrophe - wars, plagues, famines, and especially the death of rulers. This was a potential PR problem if you happened to be a king and a comet appeared.