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Radiation Reference Libraries

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Gamma-Ray Astronomy
2004-10-19 04:45:43

Gamma-Ray Astronomy -- Gamma-ray astronomy is the astronomical study of gamma rays. Long before experiments could detect gamma rays emitted by cosmic sources, scientists had known that the universe should be producing these photons. Work by Feenberg and Primakoff in 1948, Hayakawa and Hutchinson in 1952, and, especially, Morrison in 1958 had led scientists to believe that a number of...

Pulsar
2004-10-19 04:45:42

Pulsar -- A pulsar, which originally stood for pulsating radio source, is a rapidly rotating neutron star, whose electromagnetic radiation is observed in regularly spaced interval, or pulses. Pulsars are closely related to magnetars, the main difference being the strenght of the object's magnetic field. History Pulsars were discovered by Jocelyn Bell and Antony Hewish in 1967 while...

Interstellar Cloud
2004-10-19 04:45:41

Interstellar Cloud -- Interstellar cloud is the generic name given to accumulations of gas and dust in our galaxy. Depending on the density, size and temperature of a given cloud, the hydrogen in it can be neutral (HI clouds) or molecular (molecular clouds). Chemical compositions Analysing the composition of interstellar clouds is achieved by studying electromagnetic radiation that we...

Gamma-Ray Burst
2004-10-19 04:45:41

Gamma-Ray Burst -- In astronomy, Gamma-ray bursters (GRBs) are flashes of gamma rays that last from seconds to hours, the longer ones being followed by several days of X-ray afterglow. They occur at random positions in the sky several times each day. They are now believed to result from tremendous explosions in far away galaxies, during the creation of a black hole from a dying star or two...

Electromagnetic Spectrum
2004-10-19 04:45:41

Electromagnetic Spectrum -- The electromagnetic spectrum describes the various types of electromagnetic radiation based on their wavelengths. Radio, representing wavelengths from a few feet to well over a mile, is at one end of the spectrum. Gamma ray radiation is at the other end: the wavelength of the harder types is so short, in the subatomic range, that we do not have instruments...

Electromagnetic Radiation
2004-10-19 04:45:41

Electromagnetic Radiation -- Electromagnetic radiation is a combination of oscillating electric and magnetic fields propagating through space and carrying energy from one place to another. Light is a form of electromagnetic radiation. The theoretical study of electromagnetic radiation is called electrodynamics, a subfield of electromagnetism. When any wire (or other conducting object...

Drake Equation
2004-10-19 04:45:41

Drake Equation -- The Drake equation (also known as the Green Bank equation) is a famous result in the speculative fields of xenobiology and the search for extraterrestrial intelligence. This equation was devised by Dr. Frank Drake in the 1960s in an attempt to estimate the number of extraterrestrial civilizations in our galaxy with which we might come in contact. The main purpose of the...

Cosmic Background Radiation
2004-10-19 04:45:41

Cosmic Background Radiation -- The Big Bang theory predicts that the early universe was a very hot place and that as it expands, the gas within it cools. Thus the universe should be filled with radiation that is literally the remnant heat left over from the Big Bang, called the cosmic microwave background radiation, or CMB. When any patch of the sky is observed where no individual sources...

Accretion Disk
2004-10-19 04:45:41

Accretion Disk -- An accretion disk is a structure formed by material falling into a gravitational source. Conservation of angular momentum requires that, as a large cloud of material collapses inward, any small rotation it may have will increase. Centrifugal force causes the rotating cloud to collapse into a disk, and tidal effects will tend to align this disk's rotation with the rotation...

Van Allen Radiation Belt
2004-10-19 04:45:41

Van Allen Radiation Belt -- The Van Allen radiation belt is a torus of energetic charged particles around Earth, trapped by Earth's magnetic field. The presence of a radiation belt had been theorized prior to the Space Age and the belt's presence was confirmed by the Explorer I on January 31, 1958 and Explorer III missions, under Doctor James Van Allen. The trapped radiation was first mapped...

Word of the Day
barghest
  • A goblin in English folklore, often appearing in the shape of a large dog and believed to portend imminent death or misfortune.
  • A ghost, wraith, hobgoblin, elf, or spirit.
The origin of 'barghest' is not known, but it may be from perhaps burh-ghest, town-ghost, or German Berg-geist (mountain spirit) or Bär-geist (bear-spirit).
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