Visualize How an Eclipse Happens

Optics & Orbit Lab
Scale-Calculated Ray Optics & Umbral Cones
Umbra (Full Shadow) · Penumbra (Partial) · Antumbra (Annular)
💡 Drag Moon or Observer to explore shadow geometry interactively
0.00° (Syzygy)
384,400 km
0.00°
0° (Equator)

The 3 Shadow Zones

Umbra: The inner dark cone where the Sun is completely blocked. Standing here yields a Total Eclipse. Penumbra: The outer cone of partial blockage. Antumbra: Where the Moon is too small to cover the Sun, leaving the "Ring of Fire".

Why Not Every New Moon?

The Moon's orbit is tilted by 5.14° relative to Earth's ecliptic plane. Most months, the Moon passes above or below the Sun. Eclipses occur only when New or Full Moon coincides with the orbital crossing points (Nodes).

The Blood Moon Mechanics

During a Total Lunar Eclipse, Earth blocks direct sunlight. However, Earth's atmosphere acts like a lens: Rayleigh scattering filters out blue wavelengths and bends red sunset rays directly into the Umbral shadow.

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