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Last updated on April 19, 2014 at 18:42 EDT

Astronomy Reference Libraries

Page 7 of about 165 Articles
X-Ray Astronomy
2004-10-19 04:45:44

X-Ray Astronomy -- Although the more energetic X-rays (E > 30 keV) can penetrate the air at least for distances of a few meters (they would never have been detected and medical X-ray machines would not work if this was not the case) the Earth's atmosphere is thick enough that virtually none are able to penetrate from outer space all the way to the Earth's surface. X-rays in the 0.5 - 5 keV...

Very Large Telescope
2004-10-19 04:45:43

Very Large Telescope -- The Very Large Telescope (VLT) consist of four optical telescopes that have 8.4 meter aperture. The VLT is a project of the European Southern Observatory organization. It is located at the Paranal Observatory on Cerro Paranal, a 2,635-m high mountain in the Atacama desert in northern Chile. The VLT consists of a cluster four of large telescopes, and an...

Very Large Array
2004-10-19 04:45:43

Very Large Array -- The Very Large Array, one of the world's premier astronomical radio observatories, consists of 27 radio antennas in a Y-shaped configuration on the Plains of San Agustin fifty miles west of Socorro, New Mexico. Each antenna is 25 meters (82 feet) in diameter. The data from the antennas is combined electronically to give the resolution of an antenna 36km (22 miles)...

UV Astronomy
2004-10-19 04:45:43

UV Astronomy -- UV astronomy is the branch of astronomy and astrophysics which deals with objects visible in ultraviolet (UV) radiation. UV radiation ranges approximatively from 10nm (extreme UV) to 380nm (near UV). Ultraviolet line spectrum measurements are used to discern the chemical composition, densities, and temperatures of interstellar medium, and the temperature and composition...

Terrestrial Planet Finder
2004-10-19 04:45:43

Terrestrial Planet Finder -- The Terrestrial Planet Finder is a proposed NASA telescope system capable of detecting extrasolar terrestrial planets. In May 2002, NASA chose two TPF mission architecture concepts for further study and technology development. Each would use a different means to achieve the same goal - to block the light from a parent star in order to see its much smaller,...

Telescope
2004-10-19 04:45:43

Telescope -- A telescope is an instrument composed of one or more lenses or mirrors to gather and focus electromagnetic radiation. Telescopes increase the observed angular size of objects, as well as their apparent brightness. The largest telescopes are used in astronomy. A telescope was first turned on the sky by Galileo Galilei, the Italian scientist. (Telescopes used for non-astronomical...

Radio Telescope
2004-10-19 04:45:43

Radio Telescope -- In contrast to an ordinary telescope, which produces visible light images, a radio telescope "sees" radio waves emitted by radio sources located anywhere in the Universe, typically by means of a large parabolic ("dish") antenna, or arrays of them. The best-known (and largest) radio telescope is in Arecibo, Puerto Rico. A well-known radio telescope being an array of...

Radio Astronomy
2004-10-19 04:45:43

Radio Astronomy -- Radio astronomy is the study of celestial phenomena through measurement of the characteristics of radio waves emitted by physical processes occurring in space. Radio waves are much longer than light waves. In order to receive good signals, radio astronomy requires large antennas. Radio astronomy is a relatively new field of astronomical research. The earliest...

Ptolemaic System
2004-10-19 04:45:43

Ptolemaic System -- The Ptolemaic system was a system to explain the motions of the heavens, espoused by Claudius Ptolemaeus in Almagest sometime around the second century, C.E., and accepted for over a thousand years by the vast majority of people to be the correct cosmological model. Unlike earlier systems (such as 'the stars move because that is the will of the gods', or the model of...

Positional Astronomy
2004-10-19 04:45:43

Positional Astronomy -- Positional astronomy is the study of the positions of celestial objects. This is the oldest branch of astronomy and dates back to antiquity. Observations of celestial objects are important for religious and astrological purposes, as well as for timekeeping. Ancient structures associated with positional astronomy include: -- Chichn Itz -- The Medicine Wheel...