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Full Moon Declination Simulator

HK default

Full Moon is opposite the Sun, so its declination is roughly the opposite of the Sun's. In HK summer the full Moon stays lower; in winter it rides higher.

Transit altitude ≈ -1° from Hong Kong

Full Moon declination ≈ -23.4° · opposite the Sun on day 172

Before you start

Full moon is opposite the Sun, so its declination is roughly the opposite of the Sun’s. Winter full moons ride high.

Key idea

From Hong Kong, a December full moon transits higher than a June full moon.

What you see

  • Night path across the HK sky
  • Day-of-year slider

Try this

  1. Set day 172 (June) vs day 355 (December)
  2. Read the transit altitude

Why it matters in Hong Kong

Latitude 22.3°N plus opposite-Sun declination sets how high the full moon climbs.

Common mistakes

  • Thinking the Moon is always ~45° up

Glossary

Transit
Crossing the meridian — highest for that night.

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