“Read past-astronomical ponderings,
Ideas of odysseys, conjuring.
Stars: fixed in the sky,
But some objects move by–
The planets, so deemed for their ‘wandering.’”
The 16 April 2025 Bluesky limerick was another that built on the etymology of a common scientific term, from Isaac Asimov’s Words of Science and the Histories Behind Them. In this case, the term in question was “planet.”
“Read past-astronomical ponderings, /
Ideas of odysseys, conjuring.”
Throughout ancient history, seven lights could be seen to travel more seemingly-randomly across the sky, rather than making the consistent patterns that the stars did. (Asimov notes that the latter are sometimes called the “fixed stars” for this reason, since constellation shapes do not change.) These seven entities that underwent comparative “odysseys” are now known as the Sun and the Moon, and as Mercury, Venus, Mars, Jupiter, and Saturn.
“Stars: fixed in the sky, /
But some objects move by– /
The planets, so deemed for their ‘wandering.’”
Writing about these etymologies in more detail sometimes seems strangely circular (should I describe those five planets as such, in the expanded prose, before the word is officially introduced in the poem?). In this case, the last line finally links the term of interest to its original Greek derivation, since planetes means “wanderer.” Looking up the current definition reveals considerable additional precision now used with the term “planet,” from centuries of astronomical use.
It is also interesting to consider the long shadows that these seven historical observations cast on our calendar. The seven-day week was established during the time of the Roman Empire, building on much more ancient traditions. It’s possible to link the name of each of the seven historically-observed heavenly bodies to a current day of the week, via several mythological equivalencies and subsequent translations. The sun and moon are evident in Sunday and Monday, respectively; Tuesday links ultimately to Mars; Wednesday, to Mercury; Thursday, to Jupiter; Friday, to Venus; and Saturday, to Saturn.
Chemphasis 