When any patch of the sky is observed where no individual sources can be discerned, and the effects of interplanetary dust, and interstellar matter are taken into account, there is still radiation. A typical daytime sky. ... The interstellar medium (or ISM) is a term used in astronomy to describe the rarefied gas and dust that exists between the stars (or their immediate circumstellar environment) within a galaxy. ... Radiation has a variety of different meanings. ...

This radiation is known as Cosmic Background Radiation. The origin of this radiation depends on the region of the spectrum that we are observing. The most famous component is the Cosmic microwave background. This component is redshifted photons that have freely streamed from an epoch when the universe became transparent for the first time to radiation. Its discovery and detail observations of its properties are considered one of the major confirmations of the Big Bang. The Sunyaev Zeldovic theory shows the phenomena of radiant cosmic background radiation interacting with "electron" clouds distorting the spectrum of the radiation. The electromagnetic spectrum is the range of all possible electromagnetic radiation. ... WMAP image of the CMB anisotropy,Cosmic microwave background radiation(June 2003) The cosmic microwave background radiation (CMB) is a form of electromagnetic radiation that fills the whole of the universe. ... This article is about the light phenomenon. ... In physics, the photon (from Greek φοτος, meaning light) is a quantum of excitation of the quantised electromagnetic field and is one of the elementary particles studied by quantum electrodynamics (QED) which is the oldest part of the Standard Model of particle physics. ... It has been suggested that this article or section be merged with: :Timeline of the Universe. ... The deepest visible-light image of the cosmos. ... According to the Big Bang theory, the universe originated in an extremely dense and hot state (bottom). ... The Sunyaev-Zeldovich effect (SZ effect or Sunyaev-Zeldovich theory) is due to high energy electrons distorting the cosmic microwave background radiation (CMB) through the inverse Compton effect, in which some of the high energy of the electrons is transferred to the low energy photons. ...

There is also background radiation in the infrared, x-rays, etc., with different causes; most of these are ultimately attributable to unresolved individual sources. Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz...

See also

Main: Timeline of cosmic microwave background astronomy, Cosmic microwave background radiation, Galaxy formation and evolution, Magnitude, Universe Timeline of cosmic microwave background astronomy 1934 - Richard Tolman shows that black-body radiation in an expanding universe cools but remains thermal 1941 - Andrew McKellar uses the excitation of CN doublet lines to measure that the effective temperature of space is about 2. ... In cosmology, the cosmic microwave background radiation (CMB) is a form of electromagnetic radiation discovered in 1964 that radiates throughout the universe in the microwave range. ... In astrophysics, the questions of galaxy formation and evolution are: How, from a homogeneous universe, did we obtain the very inhomogeneous one we live in? How did galaxies form? How do galaxies change over time? The formation of galaxies is still one of the most active research areas in astrophysics... Categories: Orders of magnitude (length) | Length ... The deepest visible-light image of the cosmos. ...

Cosmology: Big Bang Cosmology, from the Greek: κοσμολογία (cosmologia, κόσμος (cosmos) world + λογια (logia) discourse) is the study of the universe in its totality and by extension mans place in it. ... According to the Big Bang theory, the universe originated in an extremely dense and hot state (bottom). ...

Physics: Dark matter, Dirac sea, Hot dark matter, Irradiation, Sunyaev Zeldovic Effect Since antiquity, people have tried to understand the behavior of matter: why unsupported objects drop to the ground, why different materials have different properties, and so forth. ... In cosmology, dark matter consists of matter particles that cannot be detected by their emitted radiation but whose presence can be inferred from gravitational effects on visible matter such as stars and galaxies. ... The Dirac sea is a theoretical model of the vacuum as an infinite sea of particles possessing negative energy. ... Hot dark matter is a form of dark matter, which consists of particles that travel with relativistic velocities. ... Irradiation is the process by which an item is exposed to radiation. ... The Sunyaev-Zeldovich effect (SZ effect or Sunyaev-Zeldovich theory) is due to high energy electrons distorting the cosmic microwave background radiation (CMB) through the inverse Compton effect, in which some of the high energy of the electrons is transferred to the low energy photons. ...

Other: List of astronomical topics This article needs to be cleaned up to conform to a higher standard of quality. ...

• Cosmic neutrino background
• Cosmic background