This, the fifth book (the third I’ve read) in Jack McDevitt’s Academy Series, is my favorite so far. The story has the Space Academy setting out to investigate sightings of spherical alien ships, and discovering a few nasty surprises. In this novel you will find all the imaginings of alien wonder that have made the series enjoyable, with extra helpings of adventure an mystery.
Odyssey may end up being the last book in this series, since at the end of the novel the series protagonist, Pricilla Hutchins, retires from the Academy. But you never know.