Translations:The speed of light/2/en

Jupiter and earth both revolve around the Sun. Because one Jupiter year is so much greater than one earth year, let us neglect Jupiter’s motion and consider it stationary. Also let us neglect earth’s elliptically shaped orbit, and for simplicity’s sake, let’s consider that the earth rushes in a straight line away from Jupiter for six months and then rushes directly back toward Jupiter during the remaining six months of the year. The distance traversed by earth during this hypothetical outward path is thus the diameter of the earth’s orbit, and the same distance is covered in the reverse path. In Roemer’s time, the diameter of the earth’s orbit was not known as accurately as it is today, so for the sake of this discussion, we use the modern figure of 300,000,000 km.