Four Movement · The Fifth Sun · The World That Ends in Earthquake
The Aztec cosmos ran on interlocking calendars — a 260-day sacred round, a 365-day solar year, a 52-year binding cycle. This cluster is ten apps that compute, reveal, and perform that system: calendar tools that actually work and myth interfaces that put you inside the cosmology.
Your Tonalpohualli sign, computed.
Enter any Gregorian date and get your 260-day calendar day sign and number (1-13), its presiding deity, and a traditional augury. The Tonalpohualli cycles through 20 signs paired with 13 numbers — 260 sacred combinations total.
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Where does today fall in the solar year?
Shows today's position in the Xiuhpohualli: which of the 18 veintenas you're in, its presiding deity, days remaining in the month, and how many days until the five Nemontemi hollow days.
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52 years. One great cycle.
The Calendar Round interlocks the 260-day and 365-day cycles into 18,980 unique days before any date repeats. Shows today's position in the current 52-year cycle and counts down to the next New Fire ceremony.
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Four signs carry the years in turn.
Only four Tonalpohualli day signs can open a solar year: Acatl (Reed), Tecpatl (Flint), Calli (House), Tochtli (Rabbit). Shows the current year's bearer, its number, associated direction, patron deity, and augury.
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Five hollow days. Walk carefully.
Counts down to the 5 unlucky epagomenal days ending the Aztec solar year — days when no new undertakings were begun. When inside the Nemontemi, the interface dims to a solemn dark mode.
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Which world are you living in?
Flip cards for each of the five Aztec creation eras — Jaguar Sun, Wind Sun, Rain of Fire Sun, Water Sun, and the present Movement Sun — with the presiding deity, how each world ended, and what survived to seed the next.
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The earthquake that ends the world.
Animated SVG of the Nahui Ollin / Movement glyph — the central symbol of the Aztec Sun Stone. On click, the glyph earthquakes: four petals crack outward, then reform. On mobile, responds to device tilt.
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Four corners, four colors, four fates.
Interactive compass of the Aztec quadrants: east/red/Tlaloc, north/black/Tezcatlipoca, west/white/Quetzalcoatl, south/blue/Huitzilopochtli, center/fire/Xiuhtecuhtli. Tap each direction to reveal day signs, trees, birds, and omens.
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Every birth day has a guardian.
Enter your birth date; compute your Tonalpohualli day sign; receive your patron deity — their domain, symbol, sacrificial association, and a personal augury drawn from the Borgia Codex tradition.
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The sky goes dark. Only your coal remains.
A shared group ritual: one person sets the fire time; all members see a dark screen with a live countdown. When the host triggers ignition, a single ember appears — then erupts into conflagration visible to all at once.
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The Aztec calendar was not a metaphor. It was a computational system that governed every undertaking — when to plant, when to fight, when to build a temple, when to fear the dark. These apps run the same numbers, drawn from the same anchor points. The fifth sun still moves.