NOLA SKY COCKPIT

Science exhibit · v1

LOCATION EARTH — NEW ORLEANS 29.95° N · 90.07° W · America/Chicago
LIVE

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Windshield: sky chart from New Orleans

FACING S 180°
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Celestial equator Ecliptic Horizon
Objects in view (0)

    INSTRUMENT PANEL Positions for New Orleans at the time shown above

    Exhibit

    The Moon’s 18.6-year wobble

    The Moon’s orbit is tipped about 5.1° to the ecliptic, the plane of Earth’s orbit around the Sun. Earth’s own axis is tipped about 23.4°. The two lines where the Moon’s orbit crosses the ecliptic — the nodes — slowly slide backward (westward), going all the way around in about 18.6 years.

    When the Moon’s tilt lines up with Earth’s tilt, they add: over each month the Moon swings as far as about ±28.6° of declination. That is a major lunar standstill (around 2024–2025, and again around 2043). Half a cycle later the tilts partly cancel and the Moon only reaches about ±18.3°, a minor standstill (around 2034).

    Orbital geometry · explanatory modelSeen from above the ecliptic. ☊ ascending node, ☋ descending node. Solid half of the Moon’s orbit is north of the ecliptic; the white dot marks where it reaches farthest north.
    Mean node longitude Ω (2 July)
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    Model monthly range
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    Era
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    Declination rangesThe Sun swings ±23.4° each year. The Moon’s range changes with the nodes. Bars on the right are the computed extremes for the chosen year.
    Computed extremes this year
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    Model vs. actual, 2025–2045Line: the geometric model, cos I = cos ε cos i − sin ε sin i cos Ω, using the mean node. Dots: each month’s computed northernmost declination of the Moon (Astronomy Engine). They agree within 0.2°; the small scatter is a real wobble in the Moon’s orbital tilt caused by the Sun.

    The Moon on your selected date · actual, computed

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    Common mix-ups

    • Not every full Moon is far north. The Moon reaches its northernmost point once every ~27.3 days, at whatever phase happens then.
    • Full Moons ride high in winter and low in summer, because a full Moon sits opposite the Sun.
    • A standstill doesn’t keep the Moon high. Even in a major standstill year, the Moon spends half of each month far south and low in New Orleans’ sky.