Cosmic ray
hideCosmic rays are energetic particles originating from outer space that impinge on Earth's atmosphere. Almost 90% of all the incoming cosmic ray particles are protons, almost 10% are helium nuclei (alpha particles), and slightly under 1% are heavier elements and electrons (beta minus particles). The term ray is a misnomer, as cosmic particles arrive individually, not in the form of a ray or beam of particles.
The variety of particle energies reflects the wide variety of sources. The origins of these particles range from energetic processes on the Sun all the way to as yet unknown events in the farthest reaches of the visible universe. Cosmic rays can have energies of over 1020 eV, far higher than the 1012 to 1013 eV that man-made particle accelerators can produce. (See Ultra-high-energy cosmic rays for a description of the detection of a single particle with an energy of about 50 J, the same as a well-hit tennis ball at 42 m/s [about 94 mph].) There has been interest in investigating cosmic rays of even greater energies.
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News tagged with cosmic rays
Starburst galaxy sheds light on longstanding cosmic mystery
Nov 02, 2009 |
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(PhysOrg.com) -- An international collaboration that includes scientists from the University of Delaware's Bartol Research Institute in the Department of Physics and Astronomy has discovered very-high-energy ...
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The Crab Nebula: Energy for 100,000 Suns
Nov 23, 2009 |
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(PhysOrg.com) -- A star's spectacular death in the constellation Taurus was observed on Earth as the supernova of 1054 A.D.
The Stars My Destination
Space & Earth / Space Exploration
Nov 10, 2009 |
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The Voyager spacecraft are now in the outermost layer of the heliosphere, traveling toward interstellar space - the first man-made spacecraft to travel such a vast distance from Earth.
Russian bomb physicist Ginzburg dead at 93
Nov 09, 2009 |
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Nobel Physics prize winner Vitaly Ginzburg, who helped develop the Soviet hydrogen bomb, has died at age 93, the Russian Academy of Sciences said Monday.
Fermi Telescope Detects Gamma-Ray From 'Star Factories' in Other Galaxies
Nov 02, 2009 |
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Nearby galaxies undergoing a furious pace of star formation also emit lots of gamma rays, say astronomers using NASA's Fermi Gamma-ray Space Telescope. Two so-called "starburst" galaxies, plus a satellite ...
Precise picture of early Universe supports 'dark matter' theory
Nov 02, 2009 |
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A detailed picture of the seeds of structures in the universe has been unveiled by an international team co-led by a Cardiff University scientist.
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