The answer to your question is yes, a good deal of the ‘gap’ can be filled in with astronomers and innovations important to astronomy.
Yet we will look in vain for a supporter of heliocentrism between Aristarchus of Samos in the ancient world and Copernicus in the Renaissance. So, just to be clear, there are no supporters of true, realist heliocentrism in the Middle Ages. But this doesn’t mean there is nothing to talk about “astronomically speaking”. Far from it.
First of all, it is important to remember that geocentrism and heliokinesis is just plain common sense. Even scientists in the twenty-first century speak about the sun rising and setting. This is how powerful the visual effect is. It really does look like the sun is moving across the sky and it really does feel like the earth is motionless. We know now that this is because the earth is turning on its axis and because we are moving with the earth and thus don’t feel its motion.
So powerful is the sense that the sun is moving and that the earth is still that three kinds of geocentrism survive to this day:
- Phenomenalistic geocentrism
- Astronomical geocentrism
- Navigational geocentrism
The first category is the one I’ve already described: we still speak in geocentric terms in everyday speech and when writing poetry. We still say: “look at that beautiful sunset” and “the sun is up” because this is what the phenomena look like, even though we know the scientific reality.
Astronomical geocentrism is the geocentrism assumed by astronomers who conceive of the stars as points on a dome above us. Navigational geocentrism is the practical geocentrism used by navigators on sea and in the air when, as with category 2, a dome above the earth is assumed.
If we still use these three kinds of geocentrism, imagine how hard it would have been for people in the Middle Ages and even in the early modern period shortly after Copernicus released his heliocentric model to think otherwise. This is an important point, because one of the biggest factors “holding back” heliocentrism is something that has nothing to do with religion but rather that is shared with everyone: just plain common sense.
Nicole Oresme is important to the story of astronomy and heliocentrism because he provided the conceptual apparatus for a realist heliocentrism. This is an important stepping stone to actual realist heliocentrism. Oresme contended that Aristotle’s reasons for the immobility of the earth were not ironclad. He also pointed out that humans wouldn’t notice the earth’s movement if it were moving. So although he seems to have held to a realist geocentrism himself, his challenge to the Aristotelian edifice was bold.
After him, Nicholas of Cusa (1401-1464), who became a Cardinal, wrote a work called On learned ignorance (a great title!), and in it he emphasised the limitations of human knowledge and suggested that it was extremely difficult if not impossible determine the structure and mechanics of the cosmos. Moreover, he also suggested that it might not be possible to know whether the earth was fixed or not. All of that was based on then current knowledge of course. So before Nicholas Copernicus, Nicole Oresme and Nicholas of Cusa help lay some of the ground work.
But this is only one piece of the puzzle and as we explore the history of astronomy during the one thousand years or so before Copernicus we see that the emergence of realist heliocentrism was founded on much, much more than simply switching the positions of the sun and the earth. Thus, mathematics was much more developed by 1500 AD than it had been in the ancient world. This, combined with the new Hindu number and place-value system, allowed for much more robust mathematics to be used in cosmology and astronomy. On top of that, a steady accumulation of astronomical observational data (all still naked eye of course) from the Islamic and Medieval Christian world gave early modern astronomers an advantage over their ancient counterparts.
Another example is physics: impetus theory was an important development that eventually helped lead astronomers away from Aristotelian physics and cosmology.
If we think of history of science as a march of progress from one hero to the next, we might miss some of these important structural issues. But taken together they help demonstrate that by the late Middle Ages, Christian Europe had more advanced mathematics, astronomy and other forms of science than were in existence in Antiquity.
If we go back to my chart, we can see that there are several names in it that played a role in astronomy (either directly or by contributing to mathematics and physics) during the supposed Medieval Gap in scientific progress:
John Philoponus
Brahmagupta
Bede
Al-Khârizmi
Ibn al-Haytham (my list doesn’t mention this, but he worked in astronomy too)
Grosseteste
Sacrobosco
Buridan
and of course Oresme.
But a higher resolution chart would bring others into focus. In the Islamic world, we’d want to add al-Kindi, al-Farabi, al-Biruni, ibn Bajja, ibn Rushd (Averroes) and especially Nasir al-Din al-Tusi (1201-1274). This Persian astronomer and mathematician is sometimes described as the most important astronomer between Ptolemy and Copernicus. He worked in an observatory (yes, the Muslims and Medieval Christians had observatories) in what today would be called northern Iran. He is most famous for the Tusi-couple, which he deployed to advance on Ptolemaic astronomy and Copernicus deployed it too for the same reason. You can read a brief description of the Tusi-couple and see a nice animation of it here:
Quite simply, the ancient Greeks did not have this and many other mathematical instruments that were developed in the Middle Ages.
This is one reason why it makes no sense to say (as is implied by the more extreme advocates of the Medieval Gap) that if we took out the Middle Ages ancient science would have become modern science in a few quick jumps. No, history had to happen and it took many centuries of developments to get to the point where Copernicus proposed realist heliocentrism.
We could also add further Medieval Christians to the list of those who made contributions in astronomy. The Austrian Georg von Peuerbach (1423-1461) and the German Johannes Mueller von Koenigsberg (Regiomontanus) (1436-1476) are two giants from the fifteenth century (coming near the end of the Middle Ages). Earlier still, we can point to the Alfonsine Tables of the 1250s, which were based on Islamic astronomical observations and more recent work, including that of the Jews Yehuda ben Moshe and Isaac ibn Sid. These tables served later astronomers, including Copernicus.
Now of course, not everything proposed by these Islamic and Christian astronomers and mathematics stood the test of time. But even much that did not was important to the development of science as ideas were tested and tried.
That said, as I have stressed many times, this is not to say that there was no slow down in scientific progress in the Middle Ages. The dislocations caused by the Barbarian invasions and the Viking adventures, amongst other causes, certainly put some limits on what was possible in the first half of the period. There are other factors not yet mentioned.
One is the division between cosmology and astronomy in the Middle Ages. Copernicus and others brought them together when astronomy and mathematics were elevated in the disciplinary hierarchy to the level of natural philosophy (which dealt with causation in the real world). But this division began in the ancient world. Cosmology is associated with Aristotle, Plato and Pythagoras, whereas Ptolemy helped found a kind of instrumentalist astronomy. For more on this, see John Henry, A short history of scientific thought, p. 70.
Another is what historian Peter Harrison proposed in his 1998 CUP book The Bible, Protestantism and the rise of natural science. Harrison argues that the emblematic view of nature that was dominant in Christian Europe during the Middle Ages was not conducive to an empirical view of nature. This changed, Harrison argues, with the Protestant Reformation, when we see a shift from a kind of allegorical mode of scriptural exegesis to the literal-historical mode promoted by Luther and other Protestants. In short, what Harrison sets out in his book is the idea that the shift from an allegorical approach to interpreting the Bible to a literal approach helped encourage the shift from the emblematic to empirical view of nature that we associate with the Scientific Revolution. Thus, sola scriptura helps stimulate sola natura. If Harrison is correct, and he presents a compelling case, this is a positive religious stimulus to the advance of science. Of course, this is but one factor.
There is much, much more to say, but the reading week is over and I go back to full-time teaching again tomorrow. So let me just encourage anyone interested in science during the Middle Ages to consult the professional scholarship on this period that I have already cited (I am a trained early modernist, not a Medievalist). I am referring to, amongst others, James Hannam’s book and the mighty 700-page tome The Cambridge history of science: Medieval science.
Finally, in general terms anyone reading recent surveys of the history of science (such as John Henry’s) will see that there is no Medieval Gap. So, who do we believe? The professional historians of science or the purveyors of agenda-driven pseudo-history that trot out the Myth of the Medieval Gap? I leave everyone with this example of the latter, that comes with a dark space of around 1800 years as we jump from Archimedes’ shout Eureka! to the shouts of a clerical mob with torches and pitchforks chasing poor old Galileo:
It’s well produced, but someone forgot to consult a historian of science … (and by the way, Isaac Newton didn’t have a beard).