{ "meta": { "version": 1, "notes": "Core astronomical and calendrical cycles used in astronomy, chronology, and long-term sky modeling." }, "cycles": [ { "id": "metonic-cycle", "name": "Metonic Cycle", "category": "Luni-solar Calendar", "period": "19 years", "periodDays": 6939.69, "description": "19 tropical years are approximately equal to 235 synodic lunar months.", "significance": "Foundation for lunisolar calendar reconciliation.", "related": ["Callippic Cycle", "Synodic Month"] }, { "id": "callippic-cycle", "name": "Callippic Cycle", "category": "Luni-solar Calendar", "period": "76 years", "periodDays": 27758.76, "description": "Refinement of four Metonic cycles with leap-day correction.", "significance": "Improves long-term lunisolar alignment.", "related": ["Metonic Cycle"] }, { "id": "hipparchic-cycle", "name": "Hipparchic Cycle", "category": "Luni-solar Calendar", "period": "304 years", "periodDays": 111035.04, "description": "Four Callippic cycles used as a higher-order correction block.", "significance": "Historical long-cycle refinement in ancient astronomy.", "related": ["Callippic Cycle"] }, { "id": "synodic-month", "name": "Synodic Month", "category": "Lunar", "period": "29.53059 days", "periodDays": 29.53059, "description": "Average interval between identical lunar phases, such as full moon to full moon.", "significance": "Primary month unit in lunar and lunisolar systems.", "related": ["Metonic Cycle"] }, { "id": "draconic-month", "name": "Draconic Month", "category": "Lunar", "period": "27.21222 days", "periodDays": 27.21222, "description": "Moon's node-to-node period relative to the ecliptic.", "significance": "Important for eclipse timing models.", "related": ["Saros Cycle", "Eclipse Season"] }, { "id": "anomalistic-month", "name": "Anomalistic Month", "category": "Lunar", "period": "27.55455 days", "periodDays": 27.55455, "description": "Perigee-to-perigee period of the Moon.", "significance": "Affects supermoon timing and lunar distance patterns.", "related": ["Saros Cycle"] }, { "id": "eclipse-season", "name": "Eclipse Season", "category": "Eclipse", "period": "173.31 days", "periodDays": 173.31, "description": "Interval between windows when the Sun is near a lunar node.", "significance": "Predicts clusters of solar/lunar eclipses.", "related": ["Draconic Month", "Saros Cycle"] }, { "id": "saros-cycle", "name": "Saros Cycle", "category": "Eclipse", "period": "18 years 11 days 8 hours", "periodDays": 6585.321, "description": "Near-repeat interval for similar eclipses from geometry recurrence.", "significance": "Classic eclipse prediction cycle.", "related": ["Draconic Month", "Anomalistic Month", "Eclipse Season"] }, { "id": "inex-cycle", "name": "Inex Cycle", "category": "Eclipse", "period": "29 years minus about 20 days", "periodDays": 10571.95, "description": "Longer eclipse recurrence interval connecting different saros families.", "significance": "Useful for classifying eclipse series transitions.", "related": ["Saros Cycle"] }, { "id": "solar-sunspot-cycle", "name": "Solar Sunspot Cycle", "category": "Solar", "period": "~11 years", "periodDays": 4017.75, "description": "Average magnetic activity cycle of the Sun seen in sunspot counts.", "significance": "Drives space weather and auroral activity trends.", "related": ["Hale Magnetic Cycle"] }, { "id": "hale-magnetic-cycle", "name": "Hale Magnetic Cycle", "category": "Solar", "period": "~22 years", "periodDays": 8035.5, "description": "Two sunspot cycles required for solar magnetic polarity to return.", "significance": "Long-form solar dynamo period.", "related": ["Solar Sunspot Cycle"] }, { "id": "jupiter-saturn-great-conjunction", "name": "Jupiter-Saturn Great Conjunction", "category": "Planetary", "period": "~19.86 years", "periodDays": 7255.0, "description": "Mean interval between conjunctions of Jupiter and Saturn.", "significance": "Major marker in historical chronology and sky cycles.", "related": ["Great Trigon"] }, { "id": "great-trigon", "name": "Great Trigon", "category": "Planetary", "period": "~240 years", "periodDays": 87658.0, "description": "Successive great conjunctions cycle through similar elemental triplicity patterns over centuries.", "significance": "Long-cycle structure derived from Jupiter-Saturn conjunction drift.", "related": ["Jupiter-Saturn Great Conjunction"] }, { "id": "venus-pentagram-cycle", "name": "Venus Pentagram Cycle", "category": "Planetary", "period": "8 years", "periodDays": 2921.94, "description": "Five synodic Venus cycles align closely with eight Earth years, tracing a pentagram-like pattern.", "significance": "Famous resonance in naked-eye planetary astronomy.", "related": ["Synodic Venus Cycle"] }, { "id": "synodic-venus-cycle", "name": "Synodic Venus Cycle", "category": "Planetary", "period": "583.92 days", "periodDays": 583.92, "description": "Mean interval between consecutive inferior conjunctions of Venus.", "significance": "Basis of Venus visibility phases and cycle work.", "related": ["Venus Pentagram Cycle"] }, { "id": "halley-comet-cycle", "name": "Halley Comet Cycle", "category": "Comet", "period": "~75-76 years", "periodDays": 27759.0, "description": "Orbital return interval of 1P/Halley, varying by perturbations.", "significance": "Most recognized periodic comet cycle.", "related": ["Comet Period Classes"] }, { "id": "encke-comet-cycle", "name": "Encke Comet Cycle", "category": "Comet", "period": "~3.30 years", "periodDays": 1205.0, "description": "Orbital return interval of Comet 2P/Encke.", "significance": "Classic short-period comet benchmark.", "related": ["Comet Period Classes"] }, { "id": "precession-of-equinoxes", "name": "Precession of the Equinoxes", "category": "Axial", "period": "~25,772 years", "periodDays": 9413478.0, "description": "Slow conical motion of Earth's rotation axis relative to fixed stars.", "significance": "Shifts equinox positions through zodiacal constellations over millennia.", "related": ["Great Year (Platonic)"] }, { "id": "great-year-platonic", "name": "Great Year (Platonic)", "category": "Axial", "period": "~25,772 years", "periodDays": 9413478.0, "description": "Traditional term for one full precessional cycle of the equinoxes.", "significance": "Long-duration epochal framing in astronomy and chronology traditions.", "related": ["Precession of the Equinoxes"] }, { "id": "milankovitch-obliquity", "name": "Milankovitch Obliquity Cycle", "category": "Climate-Astronomy", "period": "~41,000 years", "periodDays": 14975775.0, "description": "Variation in Earth's axial tilt angle over tens of millennia.", "significance": "Major pacing component in glacial-interglacial climate structure.", "related": ["Milankovitch Precession", "Milankovitch Eccentricity"] }, { "id": "milankovitch-precession", "name": "Milankovitch Precession Cycle", "category": "Climate-Astronomy", "period": "~19,000 to 23,000 years", "periodDays": 7665000.0, "description": "Seasonal timing shift from axial precession interacting with orbital geometry.", "significance": "Controls seasonal insolation pacing over geologic time.", "related": ["Precession of the Equinoxes", "Milankovitch Obliquity"] }, { "id": "milankovitch-eccentricity", "name": "Milankovitch Eccentricity Cycle", "category": "Climate-Astronomy", "period": "~100,000 years (plus ~405,000-year mode)", "periodDays": 36524250.0, "description": "Long-term change in orbital ellipse shape from near-circular to more elliptical.", "significance": "Dominant long pacing in Quaternary paleoclimate archives.", "related": ["Milankovitch Obliquity", "Milankovitch Precession"] } ] }