On a couple of occasions I have blogged about the publically displayed history of science ignorance of mega-star science entertainer Neil deGrasse Tyson (NdGT). On Sunday I stumbled over one his tweets, which stridently proclaimed:
If you wished upon that first Star you saw tonight in twilight,
then it will not likely come true. You wished on planet Venus
Venus is always brighter than all other planets or stars as seen from Earth. The second brightest object on the image is Jupiter
Source: Wikimedia Commons
My first reaction was that this tweet was very mean spirited and to ask myself what NdGT’s intention was in tweeting it. Then as a historian of astronomy I replied to this tweet by pointing out that from antiquity up to the beginning of the eighteenth century all illuminated celestial bodies – stars, comets, planets – were referred to as stars and so one would still be wishing upon a star. Now NdGT has a trillion sycophants followers, so the last thing I expected was a response from the great man himself to my tweet. Imagine my surprise when I got just that:
The 7 “planetes” (Greek for “wanderer”) were distinct from stars:
Sun Moon Mercury Venus Mars Jupiter Saturn.
Slam -Bam! A killer etymological put down or at least I assume that was what NdGT thought he had achieved. Unfortunately he had just ridden himself deeper into the mire. If we actually consult an etymological dictionary on the origins of the term planet we discover the following:
Planet (n): late Old English planete, from Old French planete (Modern French planète), from Late Latin planeta, from Greek planetes, from (asteres) planetai “wandering (stars),” from planasthai “to wander…
Oh dear, planet doesn’t mean wanderer in the original Greek; it means wandering star! The Greeks did indeed differentiate between fixed stars, our stars, wandering stars, the seven planets and hairy stars (I’ve always liked that one) the comets, but, and this is the decisive point, they are all stars, as I stated in the first place. Whether NdGT’s etymological error was out of ignorance or a result of deliberate quote mining I can’t say.
NdGT might have saved himself some embarrassment if he had paused for a moment to consider the etymology of astronomy, the mother discipline of his own profession, astrophysics. Astronomy is also derived from ancient Greek, as was astrology and as I pointed out in another post the two terms were, from their origin up till the late seventeenth century, synonyms. Let’s just check out those etymologies shall we.
Astronomy (n): c. 1200, from Old French astrenomie, from Latin astronomia, from Greek astronomia, literally “star arrangement,” from astron “star”
Astrology (n): late 14c., from Latin astrologia “astronomy, the science of the heavenly bodies,” from Greek astrologia “telling of the stars,” from astron “star”
So astrologia, which is the older of the two terms, means the science of the heavenly bodies, which of course includes the planets. Astronmia naturally includes the planets too, as stars.
What evidence can I bring forth that this was still the case in the Early Modern Period? I have no lesser witness than that well-known Elizabethan playwright and poet Will Shakespeare. In his tragedy Romeo and Juliet he refers to the fact that their doom has been predetermined by their astrological fate. Now an astrological horoscope determines the position of the planets along the elliptic, the apparent path of the sun around the earth, so astrology is very much planetary. So how does the good bard describe the astrological doom of his two young lovers?
From forth the fatal loins of these two foes,
A pair of star-cross’d lovers take their life
Note Romeo and Juliet are star-crossed, although it is the planets that determine their fate. In fact the expression ones fate is written in the stars is still very much used today in the English language.
I do have a last sad note for NdGT concerning his original tweet. Most people probably associate the expression ‘to wish upon a star’ with the pop song When You Wish Upon a Star originally from the Walt Disney film Pinocchio from 1940, which has been covered by many, many artists. However the tradition is much older and in fact goes back at least to the ancient Romans. The tradition says that if you make a wish when you see the first star of the evening then that wish will come true. Now the first star of the evening is ‘the evening star’ also known as the planet Venus and in fact the tradition derives from the Roman worship of Venus their goddess of love, so if you did make a wish upon seeing Venus, as NdGT claimed in his original tweet, then you would be doing exactly the right thing to have your wish come true. You are just offering up a prayer to the divine Venus.
The Birth of Venus, by Sandro Botticelli c. 1485–1486
Source: Wikimedia Commons
The saddest aspect of this brief collision on Twitter is just how many of NdGT’s sycophants followers retweeted and/or liked his etymology of the term planet tweet thinking he had brilliantly seen of the bothersome history of astronomy troll. I wouldn’t mind him spouting history of science crap if he was some brain damaged loony with 15 followers on Twitter but unfortunately he is the most well-known and influential English language science communicator in the world and his false utterances mislead and misinform a lot of trusting people.