Answer 8: Astronomically Big Words!

Reasoning

Without the clue, it is simply a case of identifying a six lettered 'astronomical' word with as many letters as possible towards the back end of the alphabet.

Using the clue however reduces the problem to a mathematical puzzle with an anagram to solve at the end, since 54,031,250 = 2x5x5x5x5x5x5x7x13x19.

Immediately from this it is possible to deduce that one letter must be an 'S' (19). Since only 5 letters remain to be found it is also easy to deduce that three of these are 'Y' (25), as any other suitable factorisation gives rise to numbers greater than 26. What is left unresolved are two letters which must be derived from 2x7x13. The only possible solutions for this are; 'M' (13) and 'N' (14), and 'G' (7) and 'Z' (26).

Hence, however unlikely it might seem, either 'SYYYMN' or 'SYYYGZ' is an anagram of the required word.