Synodic Period Calculator

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Earth & Space (astronomy, orbital mechanics, meteorology, geology, geodesy, oceanography)

Tranche

tranche-4

Evidence ID

t4-209

Ledger rows

1

No ledger note is attached.

Review findings

Formula is mathematically correct under its stated assumptions, but the alignment definition and input/data constraints must be made explicit before release.

Formula and scope findings

• The formula 1/S = |1/T1 - 1/T2| is standard for the interval between successive repetitions of the same relative orbital configuration, such as opposition-to-opposition or conjunction-to-conjunction. The phrase "successive alignments" is ambiguous: if conjunctions and oppositions are both counted as alignments, the interval can be half the stated synodic period.
• The specification does not state the required domain constraint that both orbital periods must be positive and finite.
• The planet-picker data source is underspecified: the orbital-period table needs defined values, units, and a source/version.

Unit assumptions

• T1 and T2 must use the same time unit; the output S has that same unit.
• Orbital periods are treated as fixed positive heliocentric sidereal periods, using the standard two-body approximation.
• The formula describes repetition of the same relative longitude configuration, not arbitrary geometric alignments.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The raw arithmetic formula has exploitable failure points at zero periods and equal periods, producing undefined or infinite results. A signed-period interpretation also changes whether an input is valid and can produce a different semantic result unless the convention is explicitly enforced.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "body_1": "Earth",
    "T1": 365.256,
    "T1_unit": "days",
    "body_2": "Mars",
    "T2": 686.98,
    "T2_unit": "days"
  },
  "expected_outputs": {
    "synodic_period": 779.934235,
    "unit": "days"
  },
  "working": "S = T1*T2/|T2-T1| = (365.256*686.98)/|686.98-365.256| = 250923.56688/321.724 = 779.934235 days."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json