Well, time to say more about that seemingly-overlooked detail with the next pair of clues. One beyond the planets reversed. One in airs of Earth dispersed. One that stars just cannot form. One that's rarer than them all. Lots you shouldn't in water dissolve. Mix around, this riddle to solve. Clue 1: As a few people have surmised, each of the first five lines refers to a different element. The answer, though, is nothing to do with chemistry. Clue 2: First figure out what element is "beyond the planets", then reverse that element. Clue 3: The second line refers to one of the main gases in Earth's atmosphere. Clue 4: I wouldn't expect stars to produce heavy elements by fusion, but what about light ones? Clue 5: The rare element is Astatine. No great surprise there. clue 6: The fifth line refers to one element, repeated lots of times. So the overall answer includes the same one or two letter sound repeated over and over, plus a word or words made from the previous four lines.