I’m trying to identify a science fiction novel I read about five years ago. I do not remember the author, or the title, or even most of the plot(!), but one minor background scene was very vividly described, and made a big impression on me. It concerns the phenomenon of total solar eclipses.
In this scene a character was musing on the implausibility of these eclipses. Although the Earth is an ordinary planet, and the Sun is a quite ordinary star, the coincidence of the Earth having a large moon whose diameter precisely matches the apparent diameter of the Sun to just about blot it out at an eclipse is far more improbable. It is not even a permanent situation - the Earth-Moon distance increases every year, and so in a few tens of millennia total eclipses will not occur any more. He made the point that as this is such an unusual situation, that if aliens exist, and if aliens have a concept of tourism (visiting strange and exotic locations for fun), then one point on their itinerary would surely be to view a total eclipse on Earth. With that in mind, a cheap and easy way to search for extraterrestrials would be to go to solar eclipses, and look out for eclipse-viewers of unusual appearance - they could be aliens in disguise.