What is moon runes?

Moon runes, also known as moon letters, are a special kind of rune used in J.R.R. Tolkien's fictional world of Middle-earth.

• They are invisible to the naked eye unless viewed under the specific phase of the moon in which they were written. This adds a layer of secrecy and protection to any text inscribed with them.
• The best-known example of moon runes appears in The Hobbit on Thrór's Map, which was created by Thrór. This map contains a secret message that can only be read in the light of a crescent moon on Durin's Day.
• They were invented by the dwarves, specifically by the dwarf Daeron, the rune-master of King Thingol. Daeron also invented the Cirth alphabet.
• Moon runes are described as being more difficult to create and read than normal runes, requiring specialized skills and knowledge.
• Gandalf knew how to read the moon runes on Thrór's Map.
• In-universe, the Elves, specifically Elrond, also possessed the ability to read and interpret moon runes, highlighting their ancient knowledge and connection to the history of Middle-earth.