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An alternative definition is that the penumbra is the region where some or all of the light source is obscured (i.e., the umbra is a subset of the penumbra). For example, NASA 's Navigation and Ancillary Information Facility defines that a body in the umbra is also within the penumbra.
A shadow is a dark area on a surface where light from a light source is blocked by an object. In contrast, shade occupies the three-dimensional volume behind an object with light in front of it. The cross section of a shadow is a two-dimensional silhouette, or a reverse projection of the object blocking the light.
The understory of moss is in the shade caused by the trees shadow. Shade is the blocking of sunlight (in particular direct sunshine) by any object, and also the shadow created by that object. It may refer to blocking of sunlight by a roof , a tree , an umbrella , a window shade or blind , wall , curtains , or other objects.
Earth's shadow (or Earth shadow) is the shadow that Earth itself casts through its atmosphere and into outer space, toward the antisolar point. During the twilight period (both early dusk and late dawn ), the shadow's visible fringe – sometimes called the dark segment or twilight wedge [ 1 ] – appears as a dark and diffuse band just above ...
A shadow wall is created when a light flashes upon a person or object in front of a phosphorescent screen which temporarily captures the shadow. The screen or wall is painted with a glow-in-the-dark product that contains phosphorescent compounds. [33] Publicly, these shadow walls can be found at certain science museums. [34] [35]
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outside the atmosphere of Earth. The field of astronomy features an extensive vocabulary and a ...
Thayer's 1902 patent application. He failed to convince the US Navy. The English zoologist Edward Bagnall Poulton, author of The Colours of Animals (1890) discovered the countershading of various insects, including the pupa or chrysalis of the purple emperor butterfly, Apatura iris, [2] the caterpillar larvae of the brimstone moth, Opisthograptis luteolata [a] and of the peppered moth, Biston ...
Sciography, also spelled sciagraphy or skiagraphy, is a branch of the science of perspective dealing with the projection of shadows, or the delineation of an object in perspective with its gradations of light and shade. The term comes from the Greek σκιά "shadow" and γράφειν graphein, "write".