Sky

	Email		Print
	Bookmark		Link

Sky

The sky is the part of the atmosphere

Atmosphere

An atmosphere is a layer of gases that may surround a material body of sufficient mass, by the gravity of the body, and are retained for a longer duration if gravity is high and the atmosphere's temperature is low....
or of outer space

Outer space

Outer space comprises the relatively empty regions of the universe outside the atmospheres of celestial bodies. Outer space is used to distinguish it from airspace and terrestrial locations....
visible from the surface of any astronomical object

Astronomical object

s are significant entity, associations or structures which current science has confirmed to exist in outer space. This does not necessarily mean that more current science will not disprove their existence....
.

Discussion

Ask a question about 'Sky'

Start a new discussion about 'Sky'

Answer questions from other users

Full Discussion Forum

Encyclopedia

The sky is the part of the atmosphere

Atmosphere

Outer space

Astronomical object

Daylight

Daylight or the light of day is the combination of all direct and indirect sunlight outdoors during the Daytime . This includes direct sunlight, diffuse sky radiation, and both of these reflected from the Earth and terrestrial objects....
, the sky of Earth

Earth

Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
has the appearance of a deep blue

Blue

Blue is a colour, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 440?490 Nanometre....
surface because of the air

AIR

Air is the part of Earth's atmosphere that humans breath and as such Air .Air may also refer to:...
's scattering

Scattering

Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles,are forced to deviate from a straight trajectory by one or more localized non-uniformities in the medium through which they pass....
of sunlight

Sunlight

Sunlight, in the broad sense, is the total spectroscopy of the electromagnetic radiation given off by the Sun. On Earth, sunlight is Filter ed through the Earth's atmosphere, and the solar radiation is obvious as daylight when the Sun is above the horizon....
. The sky is sometimes defined as the denser gas

Gas

In physics, a gas is a state of matter, consisting of a collection of particles without a definite shape or volume that are in more or less random motion....
eous zone of a planet

Planet

A planet , as 2006 definition of planet by the International Astronomical Union , is a celestial body orbiting a star or Stellar evolution#Stellar remnants that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared the neighbourhood of planetesimals....
's atmosphere. At night the sky has the appearance of a black surface or region scattered with star

Star

A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
s.

During the day the Sun

Sun

The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
can be seen in the sky, unless covered by cloud

Cloud

A cloud is a visible mass of Drop or frozen crystals floating in the Celestial body atmosphere above the surface of the Earth or another planetary body....
s. In the night sky

Night sky

Night sky is a commonly used term most often employed to refer to the sky as it is seen at night. The term is usually associated with astronomy, with reference to views of heavenly body such as stars, the Moon and planets that become visible on a clear night after the Sun has set....
(and to some extent during the day) the moon

Moon

The Moon is Earth's only natural satellite and the List of natural satellites by diameter satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is km, about thirty times the diameter of the Earth....
, planet

Planet

Star

A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
s are visible in the sky. Some of the natural

Natural

Natural can refer to various topics within science and mathematics, music, and other areas.In science and mathematics, natural may refer to:...
phenomena seen in the sky are cloud

Cloud

A cloud is a visible mass of Drop or frozen crystals floating in the Celestial body atmosphere above the surface of the Earth or another planetary body....
s, rainbow

Rainbow

A rainbow is an optics and meteorology phenomenon that causes a optical spectrum of light to appear in the sky when the Sun shines onto droplets of moisture in the Earth's atmosphere....
s, and aurorae. Lightning

Lightning

File:Blesk.jpgLightning is an Earth's atmosphere discharge of electricity usually accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcano or dust storms....
and precipitation

Precipitation (meteorology)

File:MeanMonthlyP.gifIn meteorology, precipitation is any product of the condensation of Atmosphere water vapor that is deposited on the earth's surface....
can also be seen in the sky during storm

Storm

A storm is any disturbed state of an astronomical body's Celestial body atmosphere, especially affecting its surface, and strongly implying severe weather....
s. On Earth

Earth

Bird

Birds are wing, Bipedalismal, endothermic , vertebrate animals that lay egg . There are around 10,000 living species, making them the most numerous tetrapod vertebrates....
s, insect

Insect

Insects are the biggest class of arthropods and the only ones with wings. They are the most diverse group of animals on the planet. They are most diverse at the equator and their diversity declines toward the poles....
s, aircraft

Aircraft

An aircraft is a vehicle which is able to flight by being supported by the air, or in general, the atmosphere, of a planet. Examples include balloons, airplanes and helicopters....
, and kites are often considered to fly

Flight

Flight is the process by which an object moves either through the air, or movement beyond earth's atmosphere , by aerodynamically generating Lift , propulsion or Lighter than air using buoyancy, or by simple ballistic movement....
in the sky. As a result of human

Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
activities, smog

Smog

Smog is a kind of air pollution; the word "smog" is a portmanteau of smoke and fog. Classic smog results from large amounts of coal burning in an area caused by a mixture of smoke and sulfur dioxide....
during the day and light radiance during the night are often seen above large cities

City

A city is an urban area with a high population density and a particular administrative, legal, or historical status.Large industrialized cities generally have advanced systems for sanitation, utilities, land usage, house, and transportation and more....
(see also light pollution

Light pollution

Light pollution, also known as photopollution or luminous pollution, is excessive or obtrusive artificial light. The International Dark-Sky Association , "The Light Pollution Authority," defines light pollution as: It obscures the stars in the night sky for city dwellers, interferes with astronomy observatory, and, like an...
).

In the field of astronomy

Astronomy

Astronomy is the science of Astronomical object and Phenomenon that originate outside the Earth's atmosphere . It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the physical cosmology....
, the sky is also called the celestial sphere

Celestial sphere

In astronomy and navigation, the celestial sphere is an imagination rotation sphere of "gigantic radius", concentric spheres and coaxial with the Earth....
. This is an imaginary dome where the sun

Sun

The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
, star

Star

A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
s, planet

Planet

Moon

Constellation

A constellation is a group of stars that appear to have a physical proximity in the sky. The stars in a constellation are often vastly distant from each other, but they appear close to each other from the perspective of Earth....
s.

See skies of other planets for descriptions of the skies of various planets and moons in the solar system

Solar System

The Solar System consists of the Sun and those Astronomical object bound to it by gravity: the eight planets and five dwarf planets, their 173 known Natural satellite, and billions of Small Solar System body....
.

Sky luminance and colors

Light from the sky is a result of the scattering

Diffuse sky radiation

Diffuse sky radiation is solar radiation reaching the Earth's surface after having been scattering from the direct solar beam by molecules or suspensoids in the Earth's atmosphere....
of sunlight, which results in a blue color

Color

Color or colour is the visual perception property corresponding in humans to the categories called red, yellow, blue and others....
perceived by the human eye. On a sunny day Rayleigh Scattering

Rayleigh scattering

Rayleigh scattering is the elastic scattering of light or other electromagnetism radiation by particles much smaller than the wavelength of the light....
gives the sky a blue gradient

Image gradient

In graphics software for digital image editing, the term gradient is used for a gradual blend of color which can be considered as an even gradation from low to high values, as used from white to black in the images to the right....
— dark in the zenith

Zenith

In broad terms, the zenith is the direction pointing directly above a particular location . Since the concept of being above is itself somewhat vague, scientists define the zenith in more rigorous terms....
, light near the horizon

Horizon

The horizon is the apparent line that separates earth from sky.More precisely, it is the line that divides all of the directions one can possibly look into two categories: those which intersect the Earth's surface, and those which do not....
. Light that comes in from overhead encounters 1/38th of the air mass that light coming along a horizon path encounters. So, fewer particles scatter the zenith sunbeam, and therefore the light remains a darker blue.

The sky can turn a multitude of colors such as red, orange and yellow (especially near sunset

Sunset

File:Sunset 2007-1.jpgSunset is the daily disappearance of the sun below the horizon as a result of the Earth's rotation. The atmospheric conditions created by the setting of the sun are also commonly referred to as "a sunset"....
or sunrise

Sunrise

Sunrise is the instant at which the upper edge of the Sun appears above the horizon in the east. Sunrise should not be confused with dawn, which is the point at which the sky begins to lighten, some time before the sun itself appears, ending twilight....
) and black at night

Night

Night or nighttime is the period of time when the sun is below the horizon. The opposite of night is day . Time of day varies based on factors such as season, latitude, longitude and timezone....
. Scattering effects also partially polarize

Polarization

Polarization is a property of waves that describes the orientation of their oscillations. For transverse waves such as many electromagnetic waves, it describes the orientation of the oscillations in the plane perpendicular to the wave's direction of travel....
light from the sky.

Sky luminance

Luminance

Luminance is a Photometry measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle....
distribution models have been recommended by the International Commission on Illumination

International Commission on Illumination

Established in 1931 and based in Vienna, Austria, the International Commission on Illumination is the international authority on light, lighting, color, and color spaces....
(CIE) for the design of daylighting

Daylighting

File:Daylighting - Skylight.jpgDaylighting is the practice of placing windows, or other openings, and reflective surfaces so that, during the day, natural light provides effective internal illumination....
schemes. Recent developments relate to “all sky models” for modelling sky luminance

Luminance

Weather

Weather is a set of all the Phenomenon occurring in a given atmosphere at a given time. Weather phenomena lie in the hydrosphere and troposphere....
conditions ranging from clear sky to overcast

Overcast

Overcast or overcast weather is the meteorology condition in which clouds obscure 95% or more of the sky.Overcast happens when the entire sky becomes covered with clouds; hence the word to describe it....
.

Sky

Sky luminance and colors

See also

External links