This article comes from a question asked by a student of mine: if the Sun radiates energy in the form of electromagnetic waves, could they shift the Earth from its current orbit on a suitable timescale? The answer to such a question is apparently obvious and trivial. Nevertheless, it requires an instructive reasoning and interesting estimates of orders of magnitude. Given the particularly positive reaction of my students to the solution given to the question, I think it is useful to report it here for the possible benefit of other students. (Contains 1 footnote.)