Illegal Alien by Robert J. Sawyer (1997). Aliens visit Earth and observe a total solar eclipse. Their scientist host speculates that Earth may be the only planet in the entire universe whose moon covers its sun perfectly (with only transits or occultations occurring on other planets). Although it is not explicitly stated in the novel, Sawyer has noted that the eclipse was the historical eclipse of August 11, 1999, which allows the reader to ascertain the time the novel takes place.