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Shadow

A shadow is a dark area on a surface where light from a light source is blocked by an opaque object.^[1] It results from the absence of direct illumination in that region, often forming a silhouette resembling the blocking object's shape. In contrast to shade, which refers to the three-dimensional volume of blocked light behind the object, a shadow is typically the two-dimensional projection observed on a receiving surface.^[2] Shadows are fundamental in optics and everyday observation, influencing phenomena from solar eclipses to architectural design, and are explored in various scientific and cultural contexts throughout this article.

Formation of Shadows

Point Light Sources

A point light source is an idealized model in geometric optics, representing an infinitely small emitter that radiates light rays uniformly and isotropically in all directions from a single point.^[3] This model assumes light propagates in straight lines without diffraction or scattering, allowing for precise predictions of shadow formation.^[3] Under illumination by a point light source, an opaque occluding object casts a sharp, complete shadow known as the umbra on a receiving surface, where no direct light rays from the source reach.^[3] The umbra forms because the object fully blocks all rays that would otherwise pass through its position, creating a region of total darkness geometrically projected behind it.^[4] Ray diagrams illustrate this process: rays emanate radially from the source, tangent to the object's edges define the shadow's boundaries, and the intercepted rays terminate at the object, leaving the umbra devoid of illumination.^[3] The shadow boundary is geometrically defined by the tangent lines drawn from the point source to the extremities of the occluding object, which extend to delineate the umbra on the surface. To derive the shadow length L, consider similar triangles formed by the light rays: the triangle from the source to the top of the object (height h over base distance d from source to object) scales to the larger triangle from the source to the surface (height h + L over base d + D, where D is the distance from object to surface). Setting the ratios equal gives \frac{h}{d} = \frac{h + L}{d + D}, which simplifies to L = \frac{h D}{d}. This equation highlights how the shadow length increases with greater distance D to the surface or shorter source-object distance d, demonstrating the projective magnification inherent to point source geometry. Representative examples of point light source shadows include those cast by distant stars, which, due to their vast separation, behave as near-ideal point sources and produce crisp umbrae observable in astronomical alignments like stellar occultations.^[4] In experimental settings, a pinhole aperture approximates a point source, enabling the formation of sharp shadows to verify geometric optics principles, such as in basic shadow projection demonstrations.

Extended Light Sources

An extended light source has appreciable size, such as the Sun or an incandescent bulb, from which light emanates from a distributed area rather than a single point.^[3] Unlike point sources, illumination from an extended source results in shadows with two distinct regions: the umbra, a central area of complete darkness where all light from the source is blocked, and the penumbra, a surrounding zone of partial illumination where light from some parts of the source reaches but others are obstructed.^[4]^[3] This dual structure arises because the occluding object blocks different portions of the extended source for points in the penumbra, leading to softer, blurred shadow edges. Ray diagrams for extended sources show overlapping umbrae from each infinitesimal point on the source, with the full umbra defined by the tangents from the source's extremities and the penumbra bounded by the inner and outer tangent envelopes.^[3] Common examples include shadows cast by the Sun during partial solar eclipses, where the Moon produces an umbra (total eclipse path) and penumbra (partial eclipse region), or everyday shadows from fluorescent lights, which exhibit fuzzy borders due to the source's finite extent.^[4]

Physical Properties

Propagation Speed

Shadows are regions of relative absence of light caused by an obstruction blocking light rays from a source. The apparent "propagation" or movement of a shadow does not involve the transport of physical matter, energy, or information; instead, it results from the dynamic reconfiguration of light rays as the obstructing object, light source, or observer position changes. This process adheres to the principles of special relativity, as no causal influence or signal exceeds the speed of light c in vacuum, approximately $3 \times 10^8 m/s.^[5] A illustrative thought experiment demonstrates how shadow patterns can appear to move faster than light. Consider an object moving with velocity v_o perpendicular to the line connecting a light source to a distant screen, where the source is at distance d from the object and the screen is at total distance D from the source (with D > d). The apparent speed of the shadow on the screen is given by v_s = v_o \cdot \frac{D}{d}. For configurations where D \gg d, such as a nearby light source and a faraway screen, v_s can exceed c even if v_o \ll c, as the shadow edge traces a path amplified by the geometry. This effect arises from the varying angles of light rays reaching different points on the screen, not from any superluminal transmission.^[5] Such counterintuitive phenomena are permissible under relativity, as they involve no transfer of information. For instance, sweeping a laser beam across the Moon can make the illuminated spot travel at speeds exceeding c—up to thousands of times c for rapid motions—because each point on the lunar surface is illuminated independently by light traveling at c from Earth. Attempting to encode a signal in the spot's motion fails, as observers on the Moon would see discrete light arrivals without discerning the sweep's timing faster than light travel time allows. This preserves the light-speed limit on communication, as affirmed in foundational relativity analyses.^[5]

Color

Shadows are regions of reduced light intensity caused by the occlusion of direct light rays by an object, resulting in an absence of illumination from the primary source. In cases where the light is monochromatic or fully blocked from all wavelengths, shadows appear black because no light reaches the observer's eye in those areas.^[6] When multiple colored light sources illuminate a scene, shadows can exhibit hues due to additive color mixing, where the perceived color in the shadowed region arises from the unblocked lights. For example, if red and blue lights dominate while green is blocked, the shadow may appear magenta, the additive mixture of red and blue. This phenomenon is demonstrated in optics experiments using colored filters on flashlights, where blocking specific wavelengths produces shadows in complementary colors relative to the filtered light; a red filter, for instance, casts a cyan shadow under white ambient illumination because the shadow receives only the non-red components of the light.^[7]^[8]^[9] Atmospheric effects further influence shadow coloration through light scattering. During the day, the blue sky tints shadows bluish because scattered blue light from Rayleigh scattering provides the primary ambient illumination in occluded areas. At sunset, however, the longer path through the atmosphere scatters shorter wavelengths more, leaving predominant red and orange light, which warms the appearance of shadows via this scattered ambient illumination.^[10]^[11] The intensity in shadowed regions can be modeled simply as I_s = I_a, where I_s is the shadow intensity and I_a is the ambient light intensity; the direct light intensity I_d is absent due to occlusion, while illuminated areas receive I_a + I_d. In practice, intensities are non-negative and ambient light prevents complete darkness.^[12]

Dimensions

Shadows manifest in two primary dimensional forms: two-dimensional planar projections and three-dimensional volumetric regions. Two-dimensional shadows are the silhouettes cast by an opaque object onto a receiving surface, such as a wall or ground, where light rays from a source are blocked, resulting in a darkened area that outlines the object's contour. These projections preserve the overall shape of the occluding object but exhibit scaling effects based on relative distances; specifically, as the object moves closer to the light source, the shadow enlarges, while proximity to the projection surface reduces its size, governed by the principles of similar triangles in ray optics.^[13] In contrast, three-dimensional volumetric shadows occupy regions in space where light propagation is obstructed, extending beyond mere surface projections into the medium itself. These are particularly visible in participating media like fog, mist, or water, where scattering reveals the shadow's depth, such as the darkened cone behind an object in hazy air or submerged volumes in aquatic environments. For extended light sources, volumetric shadows consist of an umbra—the fully shadowed core where no light reaches—and a surrounding penumbra, the transitional zone receiving partial illumination, forming conical volumes that taper with distance from the source.^[14]^[15] A notable optical phenomenon in shadow formation is inversion, where the projected image appears flipped in orientation, as seen in pinhole cameras or natural projections during solar eclipses. In a pinhole setup, light rays from an object cross at the aperture, producing an inverted silhouette on the opposite surface, with the effect explained by similar triangles relating object distance, pinhole position, and image plane. Similarly, during eclipses, gaps like those between tree leaves act as pinholes, casting inverted crescent shadows on the ground that mirror the Moon's position relative to the Sun.^[16]^[17] Mathematically, the formation of a two-dimensional shadow represents a dimensionality reduction, projecting the three-dimensional structure of an object onto a two-dimensional silhouette through orthogonal projection, which maps spatial coordinates while preserving directional alignment but losing depth information.^[18]

Natural Phenomena

Daytime and Seasonal Variations

Shadows cast by the Sun on Earth exhibit significant variations in length and direction over the course of a day, primarily due to the planet's rotation, which causes the Sun's apparent path to arc across the sky. At sunrise and sunset, the Sun's low altitude near the horizon results in the longest shadows, as sunlight travels a nearly horizontal path. As the Earth rotates, the Sun rises higher, progressively shortening shadows until they reach their minimum length at solar noon, when the Sun achieves its maximum altitude for that day and location. The direction of shadows also shifts predictably: pointing westward in the morning, aligning roughly north-south at noon (varying by latitude and season), and eastward in the afternoon.^[19]^[20] The length of a shadow from a vertical object of height h is determined by the formula L = \frac{h}{\tan \alpha}, where \alpha is the solar altitude angle (the Sun's elevation above the horizon), or equivalently, the shadow angle \theta relative to the object's vertical axis is \theta = 90^\circ - \alpha, the solar zenith angle.^[20]^[21] This relationship explains why shadows are shortest when the Sun is overhead at noon, minimizing the zenith angle and maximizing \tan \alpha. For instance, at the equator on an equinox, solar noon shadows vanish entirely for vertical objects, as \alpha = 90^\circ. Seasonal changes in shadow patterns arise from Earth's 23.5° axial tilt and its orbital revolution around the Sun, which alter the Sun's declination—the angular distance north or south of the celestial equator—ranging from +23.5° at the June solstice to -23.5° at the December solstice. In summer hemispheres, the higher average solar altitude shortens midday shadows compared to winter, when the Sun's lower path elongates them; for example, at 40° N latitude, noon shadows on a 1-meter stick are about 0.3 meters in June but extend to 2.0 meters in December.^[23] Latitude plays a key role in these variations: locations within the tropics (23.5° N to 23.5° S) experience zero midday shadows up to twice yearly when the Sun is directly overhead, while polar regions see extended periods of minimal or absent shadows in summer and prolonged darkness in winter. At the summer solstice, observers at the Tropic of Cancer (23.5° N) record no noon shadow, as the Sun is directly overhead, whereas at higher latitudes like 50° N, the maximum altitude drops to about 63.5°, yielding longer shadows even at midday.^[24]^[25]^[26] These daily and seasonal shadow dynamics have practical applications in timekeeping and navigation. Ancient Egyptians employed simple shadow clocks, or portable sundials, around 1500 BCE to divide daylight into segments by tracking a gnomon's shadow length and direction, enabling basic hourly measurements without mechanical parts.^[27] Similarly, a shadow stick—a vertical rod—allows determination of latitude by measuring the noon shadow's zenith angle on an equinox, when the Sun's declination is zero; the angle equals the observer's latitude north or south of the equator, as demonstrated in methods derived from Eratosthenes' ancient techniques.^[28]^[29] In modern urban environments, the cooling effects of shadows are influenced by the urban heat island (UHI) phenomenon, where built-up areas trap heat, amplifying temperatures by 1–7°F compared to rural surroundings. Building and tree shadows provide direct mitigation by blocking solar radiation, with studies showing shaded urban surfaces can be 4–8°C cooler than exposed ones, reducing UHI intensity; however, dense impervious surfaces in cities often limit natural shading, exacerbating heat retention and altering shadow efficacy during peak daytime hours.^[30]^[31]

Astronomical Shadows

Astronomical shadows manifest when celestial bodies obstruct light from distant sources, such as stars or the Sun, creating observable phenomena across the solar system and beyond. These shadows play a crucial role in understanding orbital dynamics and celestial alignments. In the context of our solar system, the most prominent examples involve the Earth-Moon-Sun system and interactions among planets and their satellites. Solar eclipses occur when the Moon passes between the Earth and the Sun, casting its shadow onto Earth's surface. The Moon's shadow consists of the umbra, a central region of complete darkness where the Sun is fully obscured, and the surrounding penumbra, where partial obscuration creates a dimming effect. The umbra traces a narrow path across Earth, typically up to 270 kilometers wide, allowing observers within this track to witness totality, while the broader penumbral region experiences a partial eclipse.^[32]^[33] Lunar eclipses, conversely, arise when Earth intervenes between the Sun and Moon, projecting its shadow onto the lunar surface. Earth's umbra fully engulfs the Moon during totality, often imparting a reddish hue due to atmospheric scattering of sunlight, while the penumbra causes subtler dimming.^[34]^[35] The predictability of these events relies on the Saros cycle, a period of approximately 18 years, 11 days, and 8 hours (223 synodic months), during which the Earth, Moon, and Sun return to similar relative positions, enabling recurring eclipse patterns across multiple cycles.^[36] Beyond the Earth-Moon system, shadows cast by satellites on their parent planets provide insights into gravitational interactions. For instance, Jupiter's Galilean moons—Io, Europa, Ganymede, and Callisto—periodically transit the planet's disk, projecting dark shadows observable through telescopes. These shadows, which can span hundreds of kilometers, result from the moons blocking sunlight reflected off Jupiter's clouds; rare alignments, such as the triple eclipse involving Io, Ganymede, and Callisto on March 28, 2004, highlight the precision of their orbits.^[37]^[38] The night side of Earth itself represents a vast astronomical shadow, as the planet's umbra blocks direct sunlight, enveloping half of its surface in darkness. This umbral region is bounded by the terminator line, the curving demarcation where daylight transitions to night, influenced by Earth's rotation and orbit. The terminator sweeps across the globe at approximately 1,670 kilometers per hour at the equator, marking the edge of the penumbral twilight zones.^[39]^[40] In exoplanet astronomy, shadows enable the detection of distant worlds via the transit method, where a planet passes in front of its host star, causing periodic dips in observed stellar brightness recorded as light curves. These transits, often mere fractions of a percent in depth, reveal planetary sizes and orbits; moreover, subtle variations in light curves during transits allow transmission spectroscopy to probe exoplanetary atmospheres by analyzing starlight filtered through them. Missions like Kepler and TESS have identified thousands of such systems, with atmospheric signatures—such as sodium or water vapor absorption—emerging from high-precision light curve analyses.^[41]^[42]

Technical Applications

Photography and Imaging

In the early days of photography, shadows played a crucial role in enhancing contrast and defining form, particularly in daguerreotypes developed in the 1830s by Louis Daguerre. These silver-plated images relied on the stark interplay of light and shadow to create depth and detail, as the process captured high-contrast scenes where shadows provided essential tonal separation without the aid of modern emulsions. Photographers like Daguerre himself emphasized controlled shadow placement to avoid overexposure in highlights, establishing shadows as a foundational element for visual clarity in nascent photographic art. Photographic techniques for manipulating shadows evolved to balance artistic intent with technical precision, distinguishing between hard and soft lighting. Hard lighting, produced by direct, small light sources such as a bare flash or sunlight, generates sharp, defined shadows with minimal penumbra, ideal for dramatic portraits or product photography to emphasize texture and form. In contrast, soft lighting from diffused sources like umbrellas or overcast skies creates gradual transitions in shadows, reducing harsh edges for a more flattering, even illumination often used in fashion or environmental portraits. To further control shadow intensity, fill lights—secondary sources positioned to bounce light into shadowed areas—are employed to soften penumbra and prevent deep blacks, maintaining detail without flattening the image's dimensionality. In digital imaging and computer-generated imagery (CGI), shadows are algorithmically simulated to achieve photorealism, with shadow mapping emerging as a foundational technique introduced by Lance Williams in 1978. This method projects depth information from a light source's perspective onto a 2D texture map, enabling efficient rendering of shadow boundaries in scenes with complex geometry. For more accurate hard shadows in polygonal environments, shadow volumes—developed by Frank Crow in 1977—extrude object silhouettes into volumes that intersect with the viewer's depth buffer, casting precise umbrae without sampling artifacts. These algorithms underpin modern CGI in films and video games, where real-time variants like cascaded shadow maps optimize performance for dynamic lighting. A persistent challenge in capturing shadows lies in high dynamic range (HDR) imaging, where scenes with extreme contrast between lit areas and deep shadows often result in noisy or clipped details. HDR techniques, advanced by Paul Debevec and Jitendra Malik in their 1997 work on radiance map recovery, merge multiple exposures to preserve shadow nuances, mitigating noise through tone mapping that compresses the range while retaining perceptual fidelity. This approach is essential in professional photography and cinematography, ensuring shadows contribute to narrative depth without introducing artifacts like banding or excessive grain.

Analogous Concepts

In acoustics, sound shadows form behind obstacles that block the direct propagation of sound waves, creating regions of reduced intensity analogous to optical umbrae. Diffraction at the edges of barriers allows some sound to bend into these shadowed areas, producing penumbra-like transition zones where intensity gradually increases from the deep shadow to the illuminated region. This phenomenon is particularly evident in long-range sound propagation over terrain, where models like the Fast Field Program accurately predict diffraction effects in shadow, penumbra, and bright zones behind curved surfaces.^[43]^[44] Similar shadow effects occur in water wave dynamics, as demonstrated in ripple tanks where surface waves are visualized through projected shadows. An obstacle in the tank casts a wave shadow downstream, with the umbra representing minimal wave disturbance and diffraction creating partial wave penetration at the edges, mirroring light shadow geometry. These setups illustrate how barriers disrupt plane waves, leading to observable shadow patterns on the underlying screen via refraction of light through the water surface.^[45] In quantum mechanics, wavefunction "shadows" emerge in interference experiments, where destructive interference produces dark fringes akin to shadowed regions devoid of particle detection. For instance, in the double-slit setup, the wave-like superposition of the quantum wavefunction results in probability minima that act as shadows, preventing particle arrival in those zones despite the absence of physical barriers. This interpretation highlights the non-local nature of quantum propagation, where unobserved paths contribute to the interference pattern's shadowed areas.^[46]^[47] Electromagnetic shadows, particularly for radio waves, arise in propagation scenarios where obstacles block line-of-sight paths, forming signal shadow zones that attenuate transmission. Diffraction enables partial signal leakage around edges, creating transitional regions similar to optical penumbrae, which is critical for modeling coverage in uneven terrain. These effects are quantified in propagation models, showing how buildings or hills induce deep shadows with gradual recovery via multipath diffraction, impacting wireless communication reliability.^[48] In computational domains, shadow algorithms in graphics simulate occlusion effects across wave-based rendering, drawing parallels to physical wave blocking without relying on actual light. Techniques like shadow mapping project depth information to identify shadowed pixels, efficiently approximating umbra and penumbra for realistic scene illumination. Complementarily, AI-driven shadow detection in computer vision systems employs deep learning to identify and segment shadow regions in images, treating them as occluded zones to enhance object recognition, with models achieving high accuracy on benchmark datasets.^[49]^[50]^[51]

Energy Generation

Emerging technologies have begun to harness shadows for energy generation, primarily through shadow-effect generators that exploit illumination contrasts to produce electricity. These devices operate on the principle of a Schottky junction where shadowing one region creates a potential difference, driving electron flow via the photovoltaic effect under ambient light. A foundational demonstration involved a shadow-effect energy generator (SEG) using a gold-silicon Schottky structure, achieving a power density of 0.14 μW/cm² indoors at 0.001 sun illumination with 50% shadowing, which exceeded commercial silicon solar cells by over 200% in comparable shadowed conditions and enabled powering a 1.2 V electronic watch at 0.0025 sun.^[52] In conventional solar photovoltaic (PV) systems, shadows pose a significant challenge by reducing efficiency through current mismatch and reverse current flows in series-connected modules. Partial shading typically causes average power losses of 10–15%, with severe cases exacerbating hot-spot formation and further degradation.^[53] However, hybrid PV-shading systems integrate photovoltaic elements into shading structures, such as building facades, to balance energy generation with thermal benefits; these configurations have reduced cooling demands by 14–19% while producing 770–989 kWh annually per device, enhancing overall system thermals by minimizing heat gain in shaded areas.^[54] Recent advancements have integrated shadow effects with other mechanisms for broader applications. For instance, a shadow-thermoelectric system developed in 2025 combines shadow-effect generators with thermoelectric modules to boost solar harvesting under fluctuating light, achieving improved output stability in partial shade and enabling applications such as touchless human-machine interfaces.^[55] Shadow-triboelectric nanogenerators show promise for low-light environments in Internet of Things (IoT) devices by scavenging energy from illumination contrasts alongside mechanical motion, supporting self-powered sensors with minimal ambient light requirements.^[56] These developments extend the utility of shadow-based harvesting to wearables, where motion-induced triboelectric effects can be augmented in dim conditions for sustainable powering. Key challenges in shadow energy generation include inherently low power densities, often below 1 μW/cm², which constrain output for high-demand applications, and scalability issues arising from precise control of shadow patterns and device uniformity across variable lighting. Ongoing research focuses on material optimizations, such as nanostructured interfaces, to address efficiency limitations while maintaining operation in diverse real-world scenarios.^[52]

Cultural Significance

Symbolism and Mythology

In ancient Greek philosophy, shadows symbolize illusion and the limitations of sensory perception. In Plato's Allegory of the Cave from The Republic (Book 7, circa 380 BCE), prisoners chained in a cave mistake flickering shadows projected on the wall for reality, representing the deceptive nature of the material world and the philosopher's journey toward enlightenment and true Forms.^[57] This metaphor underscores shadows as emblems of ignorance, where escaping the cave signifies ascending from superficial appearances to profound knowledge.^[58] In Hindu mythology, shadows embody duality and substitution in divine relationships. Chhaya, meaning "shadow," is depicted as the shadowy double of Surya's first wife, Sanjna, who creates her to take her place while fleeing the sun god's intense radiance; Chhaya becomes Surya's second consort and bears children including Shani, the planet Saturn deity.^[59] This narrative from texts like the Puranas illustrates shadows as extensions of the self, capable of independent agency and familial roles, highlighting themes of endurance and cosmic balance in Vedic lore.^[60] Shadows often evoke fear and cultural prohibitions, manifesting as sciophobia, the irrational dread of shadows classified as a specific phobia in psychological terminology.^[61] This anxiety can trigger intense distress from mere visual cues, rooted in evolutionary responses to darkness and the unknown.^[62] Across cultures, such fears extend to taboos, such as avoiding contact with another's shadow, believed in some traditional societies to harm the soul or invite misfortune, as shadows are seen as vital essences vulnerable to malevolent forces.^[63] Religiously, shadows convey submission and divine safeguarding. In Islam, the Quran (13:15) states that all creation, including shadows, prostrates to Allah in mornings and afternoons, symbolizing universal humility and obedience without arrogance, as shadows' movements reflect involuntary worship. Similarly, biblical passages portray God's shadow as a protective refuge, such as Psalm 91:1 ("He who dwells in the shelter of the Most High will rest in the shadow of the Almighty") and Psalm 17:8 ("Hide me in the shadow of your wings"), evoking shelter from peril and covenantal care. In modern psychology, shadows represent repressed aspects of the psyche in Carl Jung's analytical theory. The shadow archetype, introduced in works like Aion (1951) and elaborated in The Archetypes and the Collective Unconscious (Collected Works, Vol. 9i), comprises unconscious traits—often negative or instinctual—that individuals deny, yet integrating it fosters wholeness and prevents destructive projection onto others.^[64] Jung viewed this as a universal human process, where confronting the shadow leads to individuation and moral growth.^[65]

Representation in Art and Literature

Shadows have been a pivotal element in art, particularly through the chiaroscuro technique, which employs dramatic contrasts between light and shadow to create depth, volume, and emotional intensity. Developed during the Renaissance and perfected by artists like Caravaggio and Rembrandt in the Baroque period, chiaroscuro enhances realism and directs viewer attention, as seen in Caravaggio's The Calling of Saint Matthew (1599–1600), where shadows underscore the divine light illuminating the scene.^[66] In literature, shadows often symbolize the subconscious, duality, or the unknown. J.M. Barrie's Peter Pan (1911) features the protagonist's detachable shadow as a mischievous entity that must be reattached, representing the separation between childhood innocence and the adult world, while also evoking themes of identity and autonomy.^[67] Such representations highlight shadows' role in exploring psychological and existential motifs across artistic mediums.

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Hubble Spots Rare Triple Eclipse on Jupiter - NASA Science
Closer inspection by NASA's Hubble Space Telescope reveals that these spots are actually a rare alignment of three of Jupiter's largest moons - Io, Ganymede, ...
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Shadows Cast by Satellites - NASA Science
In this image, the moons and shadows that crossed Jupiter's face are labeled. The Hubble Space Telescope captured the rare triple eclipse on March 28, 2004.
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Day/Night Terminator (daily) - Science On a Sphere - NOAA
The line that separates day and night is called the terminator. It is also referred to as the "grey line" and the "twilight zone."
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Umbra – Eclipse Shadow - Time and Date
The umbra is the dark center of a shadow, where no light source is visible. The Moon's umbra causes total solar eclipses.Missing: formula | Show results with:formula
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Background - NASA Science
The dip in the light curve shows the star's light blocked by the exoplanet during the transit. The deeper the dip, the more light is blocked, the bigger the ...Why join Exoplanet Watch? · What are exoplanets? · What is the transit method?
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Transit Method - Las Cumbres Observatory
But when the planet transits, a small amount of light from the star passes through the atmosphere of the planet, which imprints its signature on the spectrum.
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(PDF) Use of the fast field program for predicting diffraction of sound ...
Aug 6, 2025 · Results from scale model experiments are in excellent agreement with the FFP calculation in the deep shadow, penumbra, and bright zone behind ...
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[PDF] Seventh International Symposium on Long Range Sound Propagation
Jul 26, 1996 · The problem of predicting the diffraction of sound in the shadow zone and in the penumbra region is a subject of considerable interest in ...
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Exploring the Science of Light - Future Scientists: The Ripple Tank
You should see wave shadows as you drip drops into the water. Generate waves with drips at one end of the ripple tank. They will begin as semicircular waves, ...
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Quantum shadows: The mystery of matter deepens | New Scientist
Jan 2, 2013 · It is as if each photon is an interfering wave that passes simultaneously through both slits. The same happens with other quantum particles: ...<|separator|>
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[PDF] The shadow interpretation versus quantum paradoxes - arXiv
This paper explores the consequences of denying the "emptiness of paths not taken,". EPNT, premise of Bernstein, Greenberger, Horne, and Zeilinger (BGHZ) in ...
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Radio propagation modeling and measurement of uneven terrain ...
Aug 5, 2025 · In conclusion, our study has demonstrated that radio wave propagation over the uneven terrain models is highly complex and affected by various ...<|separator|>
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[PDF] ~ Computer Graphics, Volume 21, Number 4, July 1987
We present a solution to the aliasing problem for shadow algorithms that use depth maps. The solution is based on a new filtering tech-.
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Unveiling Deep Shadows: A Survey and Benchmark on Image and ...
Sep 3, 2024 · This paper surveys and evaluates shadow detection, removal, and generation in images and videos using deep learning, covering tasks, models, ...
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https://www.tandfonline.com/doi/abs/10.1080/15567036.2023.2254731
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Energy harvesting from shadow-effect - RSC Publishing
Energy harvesting from shadow-effect†. Qian Zhang,‡a Qijie Liang,‡b Dilip Krishna Nandakumar, ORCID logo a Sai Kishore Ravi,a Hao Qu,a Lakshmi Suresh, ORCID ...
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Effect of partial shading on photovoltaic systems performance and its ...
On average, partial shading can cause a power loss of 10–15% in a PV system. In this paper, a comprehensive review on the theoretical background of reverse ...
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Impacts of photovoltaic shading devices on energy generation and ...
Dec 28, 2020 · Results have shown a reduction of 14%-19% on cooling loads and 770-989 kWh generated by PV devices. Altogether, the addition of PV shading ...
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Shadow enhanced self-charging power system for wave and solar ...
Jan 27, 2021 · Here we report a shadow-tribo-effect nanogenerator that hybrids tribo-effect and shadow-effect together to overcome this issue.
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[PDF] PLATO The Allegory of the Cave
Plato's famous allegory of the cave, written around 380 BCE, is one of the most important and influential passages of The Republic. It vividly.
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Plato: The Allegory of the Cave, from The Republic - Paul Brians
Nov 10, 2016 · The essential point is that the prisoners in the cave are not seeing reality, but only a shadowy representation of it. The importance of the ...
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[PDF] distribution agreement - Emory Theses and Dissertations
... chhaya, which refers to the consort of the sun god, Surya, who was the shadow of his first wife, Saranyu. There are references from at least the. 19th ...
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(DOC) Hindu Sun worship and the Physics of the sun - Academia.edu
... Surya's wife during her absence. Chaya had two sons by Surya-Sawarni ... Surya Surya Consort Sanjna and Chhaya Vaivasvata Manu, Yama, Yami, Ashvins ...
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definition of sciophobia by Medical dictionary
sciophobia Psychology Fear of shadows. See Phobia. McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
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What Is Sciophobia Or Fear Of Shadows? Causes, Symptoms And ...
Oct 12, 2020 · Sciophobia is a medical term for the shadow of fears. In people with sciophobia, even a mere thought of shadows can trigger the irrational ...
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Cultural taboos arise from a basic feature of the human mind - Psyche
Feb 10, 2025 · Unquestioned community rules on marriage, dining and even black cats often stem from our hunger to explain random events.
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[PDF] The Archetypes of the Collective Unconscious
The concept of archetypes and its correlate, that of the collective unconscious, are among the better known theories developed by Professor. Jung. Their ...
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The Jungian Shadow - The Society of Analytical Psychology
The Shadow, by Christopher Perry. In Jung's model of the psyche, there are various personified structures that interact with one another in our inner world.