Neither Copernicus nor Kepler required telescopes to come up with the
arrangement of planets around the Sun nor the accurate orbital
geometries which emerged as a refinement of the solar system
structure.Only good judgement was required to resolve the observed
motion of the planets by using plotted data against the stellar
background (including retrogrades).
What an opportunity for somebody to affirm Copernican reasoning by
using Io and its shadow cast on Jupiter -
The change in the position of the shadow on Jupiter in respect to the
position of Io is due to the way the Earth is moving towards and away
from Jupiter in our respective orbital motions around the Sun.
Why stay with 'transits' of Io crossing the face of Jupiter when there
is an opportunity to promote the Earth's orbital motion along with
This is astronomy and it is easy and enjoyable for anyone who wishes to
promote astronomy with just a little effort.