Solar CyclesEdit

Standard Earth YearEdit

Standard unit of time measurement on Earth determined by the average length of the planet's solar orbit. The year is divided up into 365.2425 planetary rotations which are in turn grouped into twelve months, most lasting 30 or 31 days. Although Mars still uses the Standard Earth Year for timekeeping, the orbital period of Mars is equal to 1.88 Earth Years and as such local seasonal cycles, such as the Martian winter are measured from that period.

Conversion TableEdit

World/Race Unit name In Earth years In Earth months
Earth/Human Year 1 12
Mars/Human Year 1.88 22.56
Ssumssha/Abbai Cheen 2 24
Brakir/Brakiri Cycle 1.17 14
Zhabar/Drazi Cycle 1.2 14.4
Gromahk/Grome Klu 1 12
Androma/Hurr Cycle 0.84 10
Shir-shraba/Hyach Shri 1.3 16
Vartas/Llort Lur 0.84 10
Septis/Markab Glantii 0.75 9
Minbar/Minbari Cycle 1.33 16
Narn/Narn 1.22[1] 14.64
Pak'ma/pak'ma'ra Tosh 3 36
Pa'ri/Yolu Teymat 1.17 14

Rotational CyclesEdit

  • An Earth day lasts 24 hours.
  • A Narn day lasts 31 hours.[2]
  • A Minbar day lasts 20 hours and 47 minutes.[3]

Other uses of "Cycle"Edit

Many worlds use the term 'cycle' to refer to their solar years, however some also use the term to refer to much smaller measurements of time, sometimes leading to confusion.[4][5][6]

  • In TKO, the Muta-Do says that the Mutai will commence in 60 cycles.
  • In Grail, Deuce tells Jinxo that he has "300 cycles" to come up with the money he owes him.
  • From these two above examples as well as the apparent amount of time that passes from the time it is said to the proscribed event, a cycle likely refers to a single rotation of Babylon 5's carousel, which spins at roughly 1 rpm.
  • In The Geometry of Shadows, Ivanova presupposes that the "cycle" the Drazi speak of in their conflict is only a week's time. The Drazi correct her, stating that a "cycle is not Drazi week; cycle is Drazi year." Though this is the Solar year meaning of 'cycle', it also means there are other legitimate uses of the term 'cycle' that are likely denoted by the context in which they are used.


  1. By Any Means Necessary - 12.2 earth years equals 10 Narn years
  2. A View from the Gallery - G'Kar mentions the bombings lasting 31 hours a day.
  3. To Dream in the City of Sorrows - Explicitly stated. Sinclair noted how it caused him some problems with his sleep pattern.
  4. Grail - Deuce gave jinxo "300 cycles" to pay up. Given the timescale of the episode, in this instance a cycle probably equates to 1 minute. Thus 300 cycles equals 5 hours.
  5. The Geometry of Shadows - Ivanova confused a cycle for a Drazi Week, when it was in fact a year
  6. Babylon Squared - in July 2258 Delenn said it had been 10 cycles since the death of Dukat.

Other SourcesEdit

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