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Astronomy

WIMP -- In astronomy, WIMPs, or weakly interacting massive particles, figure into one explanation of the dark matter problem. The particles are called "weakly interacting" because they seem not to have much interaction with normal matter (electrons...

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 atmosph...

Tycho Brahe -- Tycho Brahe (December 14, 1546 - October 24, 1601) was a Danish astronomer. He had Uraniborg built; which become an early "research institute". For purposes of publication, Tycho owned a printing press and paper mill. His best known assi...

Active Optics -- Active optics is a relatively new technology for astronomic telescopes. Most modern telescopes are reflectors, with the primary element being a very large mirror. Historically, a fixed weight-to-diameter relation was used to build ...

Adaptive Optics -- Adaptive optics is a technology to improve the performance of Earth-based telescopes, reversing the effect of atmospheric distortions. When light from a star or another astronomical object enters the Earth's atmosphere, the diffe...

Amateur Astronomy -- Amateur astronomy, also called backyard astronomy, is a hobby whose participants enjoy watching the night sky (and the day sky too, for sunspots, eclipses, etc.), and the plethora of objects found in it, mainly with portable telesc...

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 Feenber...

Hertzsprung-Russell Diagram -- In stellar astronomy, the Hertzsprung-Russell diagram (H-R diagram) shows the relation between the absolute magnitude and the spectral types of stars. It was invented around 1910 by Ejnar Hertzsprung and Henry Norris Russ...

Interferometry -- Interferometry is the applied science of combining two or more input points of a data type, such as optical, and combine these data to form a greater picture based on the combination of the two sources. This technique is the basis...

Light Pollution -- Light pollution refers to excess light, created by human activities, that brightens the night sky enough to hide many stars from observers. For the average person, light pollution means that even on a clear, moonless night, only ...

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...

Parabolic Mirror -- A parabolic reflector or parabolic dish is a reflective device formed in the shape of a paraboloid of revolution. Parabolic reflectors can either collect or distribute energy such as light, sound, or radio waves. The parabolic r...

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 ...

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 si...

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 a...

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 telescope...

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 devel...

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 me...

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 2...

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 Parana...