A Planet-Less Nautical Astronomy

From the RUTTER crew conversations logbook, preserved for posterity: We have been wondering at the early modern pilots of the Indian Ocean, who famously used complex combinations of stars to navigate by night—a catalogue of about 150 celestial bodies was in their treatises— but, and here’s the question, without ever even bothering to mention the planets. By this I mean the five known at the time, Mercury, Venus, Mars, Jupiter and Saturn. The same planets without which Ptolemy’s astronomy would have been reduced to nothing, and the same planets without which astrology would have been unimaginable.

The reason for this absence is obvious, and it is a nice etymological lesson. A planet, as is well known, means in the original Greek a “wanderer”, a “vagabond”. Now, if you are going to depend on guidance through the night and through the vast expanse of the ocean, you cannot rely on something changeable. You need fixed, unchanging points of reference, and this is exactly what was provided by the night sky, those wanderers excepted.

How bright they are, and unflickering! We have just been witnessing in Lisbon the approach and conjunction of Venus and Jupiter, every day, in the sunset sky, very impressive. And yet for all their steady light, they are not good for navigation: one day they are here, next day there, one day going straight, next day retrograding… They are strong, but fickle. The importance that they have in the astrological view of the cosmos is quite indicative of the variable state of the world: matters of the world and we are not ruled by stars, which would make us constant, but by those wandering bright lights.

Photo: Jorge Rodrigues da Silva

The lack of importance that the planets have in navigation is, in turn, quite indicative of the nature of this craft, and of how special is the state of being at sea and being in transit to a destination: there is peril, and there is the urgency to reach a place, and so all the variable concerns of the pilot are subordinate to accomplishing his task, as Ibn Mājid says, “going and returning with the passengers and the cargo safe.” [JA]