One of the real benefits of teaching is the questions students ask. Recently one exposed my shameful forgetfulness of what I once knew about the history of science :(

The question ran something like this:

The emperor Domitian had a coin made to celebrate his son's divinisation showing the boy sitting on a globe - presumably representing the earth, with 7 stars around him.

The Romans like other ancients believed the Earth to be flat.

Why was a globe used?

Of course, the image is typical of a tradition of picturing gods seated on globes, see for example the coin representing Victory seated on a globe (from the page on coins from the time of Nero from the Classics Dept. at Monmouth College).

The Romans regularly used "orbis", a circle, ring, or disk, in the phrase orbis terrae, terrarum "the circle of the world" to mean the whole earth.

For of course, as I had forgotten, and the student did not know, the story which claims that before Columbus people "all" believed that the Earth was flat is simply a myth.

A Greek, Eratosthenes (c 276 to 195 BCE) estimated the Earth's circumference by getting measurements taken of the Sun's position in the sky at two different places Syene (now Aswan, Egypt) and Alexandria which is directly north of Syene. From the difference (and assuming that the Sun is so far away that light is parallel in the two places) he got a value close to the current measurements. (There is a good well documented presentation of this and the whole history of the "flat earthers" on Donald Simanek's site.)

Most early Christians, in the Roman empire, largely following Aristotle, accepted that the earth was round. Though at least Tertullian and others argued that the Bible spoke of it having four "corners" etc. so it must be flat.

So it is no surprise that Roman coins pictured the globe as round, that was the majority view among educated people at the time! And indeed continued to be, though perhaps not for much longer if the "Creation Scientists" have their way and require us all to use Scripture in ways that were never intended to teach us "science".