The ISS sailed over my country, Sri Lanka on the eve of yesterday (14th October), and there was some news coverage on the event. While the reporting wasn't particularly scientific or even factual (I'm still cringing because one of the news outlets called it the International Space Center), I was happy that such incidents gets a news coverage and possibly inspires kids for space exploration.
However, I was wondering if this incident was newsworthy, because I know for a fact that the ISS does around 15.5 orbits of 92 minutes a day. So I am thinking this shouldn't exactly be a rare occurrence, and the ISS should come back to approximately the same projected surface location on Earth pretty quickly (not exact location, but within ~250km on ground of the projected path of a previous orbit). However, I don't have the know-how to do the math.
What sort of time period does it take for the ISS to come close to a previous orbit, such that the distance between projections of the two orbits are within ~250km on the ground?