History of Arda - Valian Years

In the fictional works of J. R. R. Tolkien, the Valian Years are used to measure the passage of time after the arrival of the Ainur in Arda. This definition of a year, named for the Valar, continued to be used during periods that used different definitions of a year, such as the Years of the Lamps, the Years of the Trees, and the Years of the Sun. The Valian years continued to be measured in Aman after the first sunrise, but Tolkien provided no dates for events in Aman after that point. The account in Valian years is generally not used when describing the events of Beleriand and Middle-earth.

In the 1930s and 40s Tolkien used a figure which fluctuated slightly around ten before settling on 9.582 solar years in each Valian year. However, in the 1950s Tolkien decided to use a much greater value of 144 solar years per Valian year, and included this figure in The Lord of the Rings appendices as the length of the elven year (the yen).

This new figure elongates the established timeline: The Flight of the Noldor took 5 Valian Years (~50 of our years); with the new figure this would be 'translated' into ~700 of our years. Some commenters suggest that these new figures would be too long if applied directly to the existing dates and therefore the new definition is a wholly different measure than the one used in the timeline and cannot be applied directly. In contrast, Tolkien described time as having flowed more slowly in Aman, such that a Valian year there would 'feel' like the passage of a single solar year in Middle-earth despite being much longer.