For years grade school students faced this question on their science tests: "True or False—The famous rings of the planet Saturn are composed of solid material." If the students marked "true," they lost credit, because the "truth" was that Saturn’s rings were composed of gas or dust. Then, in 1973, radar probes revealed that all those wrong answers had been right. Saturn’s rings are, in fact, composed of solid matter.12 This confusing case seems to suggest that the truth changed. Did it really? Explain.