The term 'Many, Many Moons' can be broken down into four crossword solutions: EONS (4 letters), AEON (4 letters), EON (3 letters), and YEARS (5 letters). EONS are the longest units of geological time, lasting millions or billions of years. An AEON is a very long period of time, usually referring to an indefinite and very long period of time. An EON is a very long period of time, usually lasting one billion years. Finally, years are the shortest unit of time, lasting 365 days. All of these terms refer to a very long period of time, which is what the phrase 'Many, Many Moons' implies.