TECHVEINNATARAJAMerchant Navy LMS
ES-02 practice — not an approved assessment

Solar, apparent and mean solar day

Learning outcomes & permitted supports
  • Explain why a solar day depends on Earth's rotation plus orbital advance.
  • Distinguish the apparent and mean Sun, LAT and LMT, and use the equation of time with correct sign.
  • Predict meridian-passage timing and convert it through LMT → GMT → ZT.

Supports in this lab: live physical model, engine readouts, EoT curve. No almanac needed; all values computed and validated.

The physical system

♈ to First Point of AriesSunEarth
Solid black stroke on Earth = your meridian. Transit happens when it points along a ray — the clocks and this picture always agree (same engine).

Two suns, two clocks

12 (noon)001806
Apparent time (LAT) — 05:55:39
12 (noon)001806
Mean time (LMT) — 06:00:00

Engine readout (lon 0°)

Equation of time−4m 21s
Sun transits at (LMT)12:04:21
Sun declination13° 42.9′ N
Sun GHA268° 54.7′
Semidiameter15.8′
Earth–Sun distance1.0127 AU

Equation of time through the year

-15m-10m-5m+5m+10m+15m0JanFebMarAprMayJunJulAugSepOctNovDec−4m 18s
Equation of time, 2026 (apparent − mean). Above the baseline the sundial runs fast — the Sun transits before 12:00 LMT. Click or use ←/→ to scrub.

Why the curve looks like this — the two causes, separated

-15m-10m-5m+5m+10m+15mJanFebMarAprMayJunJulAugSepOctNovDec● ellipse only● true total● tilt only
Two causes, one curve: the ellipse wave (one cycle, ±7.7m — Kepler's speed-up) plus the tilt wave (two cycles, ±9.9m — ecliptic→equator projection) sum to the true equation of time. February's deep minimum and November's high peak are just the two waves agreeing. Earth's rotation contributes nothing — it is uniform.
My notebook — ES-02 (0)

All notes & standing →

Every interaction here is recorded as an ordered evidence trail — 0 events this attempt.