Umbra, penumbra and antumbra facts for kids

Umbra, penumbra and antumbra of Earth and images that could be seen at some points in these areas (note: the relative size and distance of the bodies shown are not to scale).

Umbra (A) and penumbra (B)

The umbra, penumbra and antumbra are three distinct parts of a shadow

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.

Umbra

Umbra, penumbra, and antumbra formed through windows and shutters

The umbra (Latin for "shadow") is the innermost and darkest part of a shadow, where the light source is completely blocked by the object.

Penumbra

The penumbra (from the Latin paene "almost, nearly") is the region in which only a portion of the light source is obscured by the objects body. An observer in the penumbra experiences a partial eclipse.

Scale diagram of Earth's shadow, showing how the umbral cone extends beyond the orbit of the Moon (the Moon is indicated by the yellow dot).

Earth's umbra, as seen during a partial lunar eclipse

Antumbra

The antumbra (from Latin ante, "before") is the region from which the objects body appears entirely within the disc of the light source. An observer in this region experiences an annular eclipse, in which a bright ring is visible around the eclipsing body. If the observer moves closer to the light source, the apparent size of the occluding body increases until it causes a full umbra.

See also

In Spanish: Umbra, penumbra y antumbra para niños