page_title: Umbra, penumbra and antumbra
section_title: Umbra
hierarchical_section_title: Umbra, penumbra and antumbra / Umbra
caption_attribution_description: English: Example of antumbra using window and shutters Français&#160;: Mise en évidence des ombres, pénombres et anté-ombres par une fenêtre avec volets et rideau
context_page_description: The umbra, penumbra and antumbra are three distinct parts of a shadow, created by any light source after impinging on an opaque object. Assuming no diffraction, for a collimated beam of light, only the umbra is cast.
  These names are most often used for the shadows cast by celestial bodies, though they are sometimes used to describe levels, such as in sunspots.
context_section_description: The umbra (Latin for "shadow") is the innermost and darkest part of a shadow, where the light source is completely blocked by the occluding body. An observer within the umbra experiences a total eclipse. The umbra of a round body occluding a round light source forms a right circular cone. As viewed from the cone's apex, the two bodies appear the same size. The distance from the Moon to the apex of its umbra is roughly equal to that between the Moon and Earth: 384,402 km (238,856 mi). Since Earth's diameter is 3.70 times the Moon's, its umbra extends correspondingly farther: roughly 1,400,000 km (870,000 mi).
caption: Umbra, penumbra, and antumbra formed through windows and shutters
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