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Scintillation (astronomy) - Wikipedia, the free encyclopedia Scintillation or twinkling are generic terms for rapid variations in apparent brightness or color of a distant luminous object viewed through the atmosphere. It is clearly established that almost all scintillation effects are caused by anomalous refraction caused by small-scale fluctuations in air density usually related to temperature gradients. Scintillation effects are reduced by using a larger receiver aperture, this effect is known as aperture averaging. en.wikipedia.org /wiki/Scintillation_(astrophysics)   (256 words)

Interplanetary Scintillation Array - Wikipedia, the free encyclopedia The Interplanetary Scintillation Array (IPS Array or Pulsar Array) was built at the Mullard Radio Astronomy Observatory in 1967 and originally covered four acres (16,000 m²). Sheep are used to keep grass away from the aerials as a lawnmower would not fit. It was designed by Antony Hewish to measure the high-frequency fluctuations of radio sources, originally for monitoring interplanetary scintillation. en.wikipedia.org /wiki/Interplanetary_Scintillation_Array   (235 words)

NRL - Astronomy HIIS provided the first measurements of the ionic charge state of solar energetic Fe ions at very high energies; provided new observations of trapped anomalous cosmic rays; and collected a sample of 'ultraheavy' galactic cosmic rays roughly three times larger than accumulated in earlier experiments. X-ray Astronomy - NRL astronomers made the first positive identification of discrete sources of stellar X rays in 1963. OSSE - NRL's Oriented Scintillation Spectrometer Experiment (OSSE) was launched aboard NASA's Compton Gamma Ray Observatory in 1991 and reentered Earth's atmosphere in June, 2000. www.nrl.navy.mil /content.php?P=ASTRONOMY   (170 words)

Zoom Astronomy Glossary: A Scintillation in caused when the star's light is distorted by the Earth's atmosphere. Scintillation is greater for bright stars that are low on the horizon. Astronomy is the scientific study of space, including the planets, stars, galaxies, comets, and nebulae. www.enchantedlearning.com /subjects/astronomy/glossary   (4918 words)

Highbeam Encyclopedia - Search Results for scintillation   (Site not responding. Last check: 2007-10-22) scintillation counter SCINTILLATION COUNTER [scintillation counter] device for detecting and measuring radiation by means of tiny visible flashes produced by the radiation when it strikes a sensitive substance known as a phosphor (see phosphorescence). pulsar PULSAR [pulsar] in astronomy, a neutron star that emits brief, sharp pulses of energy instead of the steady radiation associated with other natural sources. Describing diamond beauty: assessing optical performance: the vocabulary of diamond beauty involves the historical terms, brilliance and fire, and the more recent term, scintillation. www.encyclopedia.com /SearchResults.aspx?Q=scintillation   (329 words)

Zoom Astronomy Glossary: S He was a great popularizer of astronomy, was involved in many NASA flights and SETI, and also pioneered the field of exobiology. Scintillation is the twinkling of stars (fluctuation of intensity) seen through a planet's atmosphere. Stellar scintillation is the twinkling of stars (fluctuation of intensity) seen through a planet's atmosphere. www.enchantedlearning.com /subjects/astronomy/glossary/indexs.shtml   (8147 words)

Starry Night Scintillation, the technical term for the twinkling of stars, is defined as the rapid and irregular variation of intensity of celestial objects. Interplanetary scintillation (IPS) is the rapid variation in amplitude of radio waves caused by the interaction of the solar wind with the Earth’s ionosphere, a layer in the Earth’s upper atmosphere in which many of the atoms are ionized (the atom has lost electrons). As we continue to enjoy the phenomenon of scintillation, astronomers will continue to study this phenomenon, improving upon their understanding of the nature of scintillation and scintillating sources, and developing new techniques to minimize its effects. www.astrophys-assist.com /educate/starry/starrynight.htm   (3974 words)

AllRefer.com - pulsar (Astronomy, General) - Encyclopedia pulsar, in astronomy, a neutron star that emits brief, sharp pulses of energy instead of the steady radiation associated with other natural sources. The study of pulsars began when Antony Hewish and his students at Cambridge Univ. built a primitive radio telescope to study a scintillation effect on radio sources caused by clouds of electrons in the solar wind. Because this telescope was specially designed to record rapid variations in signals, in 1967 it readily recorded a signal from a totally unexpected source. reference.allrefer.com /encyclopedia/P/pulsar.html   (528 words)

Joseph Lazio: Turbulence in the Interstellar Medium Scintillation (intensity fluctuations) results from the passage of a light wave through a random medium (i.e., one in which the refractive index varies randomly). A common example of scintillation is the twinkling of starlight, resulting from visible light passing through the Earth's atmosphere. Scintillation is also observed at radio wavelengths during observations of pulsars and extragalactic radio sources. patriot.net /~jlazio/turbulence.html   (1334 words)

Dainis Dravins (Lund Observatory) Astronomy could be the oldest science, and the twinkling of stars was one of the earliest celestial phenomena studied by man. Its cause has been sought for millennia: not until Robert Hooke (Micrographia, London 1665) was its atmospheric origin explained in any detail. The understanding in terms of optical physics was developed during the 1960's, while current studies focus on scintillation properties in the non-ideal and rapidly changing atmosphere. those bright scintillations near the Horizon, are not by much so quick and sudden in their consecutions of one another, as the nimbler twinklings of Stars nearer the Zenith. www.astro.lu.se /~dainis/HTML/HISTORY.html   (227 words)

University of Glasgow: IPS The Astronomy and Astrophysics group in the Physics and Astronomy Department of the University of Glasgow holds the primary data from the New Cambridge IPS Survey (1990 to 1994). These scintillations reveal density fluctuations in the interplanetary medium and can be processed to produce daily maps of the sky, highlighting regions occupied by unusually low or high density solar wind. Scintillation is expressed as the index g on a logarithmic scale. radio.astro.gla.ac.uk /ips/ips.htm   (433 words)

Institute of Mathematical and Physical Sciences   (Site not responding. Last check: 2007-10-22) However the scintillation in this case is mostly due to moving density variations in the solar wind. It is easiest to imagine the solar wind as consisting of a series of "blobs" of higher density plasma moving outwards from the Sun. Since the scintillation pattern is only due to components of the solar wind moving perpendicular to the line of sight, there is a "cos(q)" effect to take into account when trying to calculate the solar wind velocity from the time lag of the scintillation pattern (figure four). www.aber.ac.uk /physics/research_ips.shtml   (1171 words)

Solar-Ionosphere Connection: Physics with the 20 MHz Antenna Radio scintillation caused by ionospheric scintillation will have typical p of -2.6 and those due to plasma bubbles will have p values from -2 to -8, with an average of -4 (notes 1 and 3). However, ionospheric scintillation is generally expected only at night and mostly between sunset and midnight, and then only significantly in the polar and equatorial regions. It is called interplanetary scintillation (IPS) and it is not restricted to the nocturnal rearrangements of the ionosphere (http://radio.astro.gla.ac.uk/ips/ips.htm). home.earthlink.net /~jcmannone/id7.html   (3395 words)

Antony Hewish - Autobiography My decision to begin research in radio astronomy was influenced both by my wartime experience with electronics and antennas and by one of my teachers, Jack Ratcliffe, who had given an excellent course on electromagnetic theory during my final undergraduate year and whom I had also encountered at Malvern. Following our Cambridge discovery of interplanetary scintillation in 1964 I developed similar methods to make the first ground-based measurements of the solar wind and these were later adopted in the USA, Japan and India for long term observations. She was quick to spot the week to week variability of one scintillating source which I thought might be a radio flare star, but our more detailed observations subsequently revealed the pulsed nature of the signal. nobelprize.org /nobel_prizes/physics/laureates/1974/hewish-autobio.html   (977 words)

Astronomy - Antarctica: best seeing on Earth - Francis Reddy Antarctica is uniquely suited for optical and infrared astronomy, noted Roger Angel, director of the Steward Observatory Mirror Laboratory in Tucson. A critical piece of hardware for AASTINO was the Multi-Aperture Scintillation Sensor (MASS) invented by Andrei Tokovinin — also on Lawrence's team — and colleagues at the Sternberg Astronomical Institute of Moscow University. This unit could be a camera, a device that holds optical fibers for capturing the light, or a secondary mirror reflecting light through the primary's central hole. www.astronomy.com /asy/default.aspx?c=a&id=2461   (1081 words)

Cornell News: Tracking pulsars Now, Cordes and Rickett have found a way to calculate both the distance and the speed of these rocketing stars by measuring the rate at which they twinkle and combining this with their angular motion in the sky as measured by the VLBA. ISS is analogous to the twinkling of stars but occurs in the radio signals from celestial sources rather than in optical light. But radio twinkling, or scintillation, results as radio waves travel through interstellar gas and the turbulence that resides in it. www.news.cornell.edu /releases/June98/scintillation.deb.html   (609 words)

Interstellar Scattering and Scintillation as Tools in Radio Astronomy   (Site not responding. Last check: 2007-10-22) In recent years Interstellar Scintillation (ISS) has been identified as causing variations in flux density in a variety of radio astronomical observations. Although this ``Galactic seeing'' effect is in some ways a nuisance, ISS is also a valuable tool that provides information on radio source structure at angular scales well beyond the reach of all current interferometers. However, the local strength of turbulence is itself non-uniform, with localized enhancemnents by more than six orders of magnitude, whose physical origin is still obscure. www.aas.org /publications/baas/v30n2/aas192/abs/S046001.html   (298 words)

Curious About Astronomy: Why do stars change colour when they twinkle? This is because of scintillation ("Twinkling") as the light passes through the atmosphere of the Earth. If you have a question about another area of astronomy, find the topic you're interested in from the archive on our site menu, or go here for help. Ask an Astronomer is hosted by the Astronomy Department at Cornell University and is produced with PHP and MySQL. curious.astro.cornell.edu /question.php?number=239   (156 words)

Department of Physics and Astronomy: Course Information Lectures, demonstrations in astronomy, laboratory experiences in celestial mechanics and light and observations through an optical telescope in an integrated lecture-laboratory sequence. Included is a survey of physics, astronomy and chemestry in an integrated lecture-laboratory sequence. Included is a survey of physics, astronomy and chemistry in an integrated lecture-laboratory sequence. www.olemiss.edu /depts/physics_and_astronomy/courses.html   (1312 words)

Research   (Site not responding. Last check: 2007-10-22) The concept of acoustical scintillation, well known through its electromagnetic analogue in radio and optical astronomy, turns out to be an effective means for probing currents and turbulence. The path-averaged turbulent kinetic energy dissipation (per unit mass) is estimated in a shallow tidal channel using acoustical scintillation analysis. The results show that turbulent velocity fluctuations are the dominant (~95%) component of he observed acoustic scintillation, leading to estimates of the path-averaged turbulent energy dissipation, which rises and falls with the tidal current. pulson.seos.uvic.ca /scint.html   (738 words)

UCSD ECE Faculty: Barney J. Rickett   (Site not responding. Last check: 2007-10-22) Wave propagation through random media, in particular in radio astronomy where the irregular plasmas of the solar wind and the interstellar medium cause serious perturbations. His early discovery of interstellar scintillation has been followed by a thorough exploration of how waves are delayed and scattered on time scales ranging from microseconds to years. Gupta, B. Rickert, and A. Lyne, "Refractive interstellar Scintillation in Pulsar Dynamic Spectra," Mon. fleece.ucsd.edu /~rickett   (197 words)

Astronomy Department Calendar - Spring 1999 Astronomy Department colloquia are held on Mondays at 4pm during most weeks in the academic year. For these colloquia, coffee is served in the Astronomy Building lounge a half hour before the start of the talk. Other goings-on around the Astronomy Department, such as hirings and awards can be found on the news page. www.astro.virginia.edu /events/calendar.php?sem=Spring&year=1999   (716 words)

Chandra :: Chronicles :: Major Milestones In X-ray Astronomy :: June 6, 2002 June 6, 2002 :: In September, 1949, a team led by Herbert Friedman of the Naval Research Laboratory detected weak X-ray emission from the solar corona, the hot outer layers of the Sun's atmosphere. Extremely rapid variability observed by RXTE may be evidence for the dragging of space by strong gravity in the vicinity of fl holes. Of particular importance are discoveries relating to the life cycles of stars, the number and nature of fl holes in the universe, the generation by neutron stars of high energy matter and anti-matter particles, and the formation and evolution of galaxies. chandra.harvard.edu /chronicle/0202/40years/index.html   (1452 words)

Correlative study of neutral winds and scintillation drifts measured near the magnetic equator Measurements of the thermospheric neutral wind at Arequipa, Peru, and observations of the drift of the irregularities at Ancon, Peru, are used to study the coupling that exists between ions and neutrals at equatorial latitudes and the variability of this coupling as a function of the occurrence of scintillations. We also find that the meridional wind shows a modest dependence on the scintillation activity during the June solstice. During scintillation events and between 2000 and 2400 LT the averaged meridional wind observed to the south and north of Arequipa exceeds their corresponding no-scintillation values by 20 m s www.agu.org /pubs/crossref/2002/2001JA000042.shtml   (352 words)

DOC: Resources: Atmosphere, Seeing, Weather This spreading of the light into a 'seeing disk' is caused by many small angle scatterings, and hence has a two-dimensional Gaussian distribution. If the star is scintillating faster than your eye's time resolution (about 0.1 second), it will appear to shine steadily even if a telescope shows it as a hazy fuzzball." Mikesell, Hoag and Hall (1951) "The scintillation of starlight" Journal Optical Society of America, 41, 689-695. www.fortunecity.com /roswell/borley/49/atmosph.htm   (1305 words)

>Radio Astronomy Research An important feature of low frequency radio astronomy is the effect of the interstellar and interplanetary media on wave propagation. By combining scintillation ('twinkling') measurements of distant quasars and radiogalaxies with models of plasma dynamics we can infer much about the nature of both. A research programme has recently begun to investigate the feasibility of constructing very broad-band, multi-beam telescopes for use in scintillation and pulsar astronomy. www.astro.gla.ac.uk /research/theme-radio.shtml   (474 words)

Astronomy :: MPI Informatik You can find some information material about astronomy, the current weather conditions at the MPI Informatics Saarbruecken and the status of our Astronomical Observatory. It is due to the moving layers of air in the atmosphere situated in the starlight's way. This twinkling causes long exposure images of celestial objects to be unsharp; by taking a series of numerous very short-exposure images we can freeze this scintillation and obtain pictures featuring much sharper details. www.mpi-sb.mpg.de /~lintu/astronomy.html   (433 words)

Radio Astronomy To the uninitiated, radio astronomy is usually associated with giant parabolic dishes listening for ET to broadcast some cryptic transcendental number. Of course, this is not what radio astronomy is all about. The invention of the transistor, with its impact on telecommunications and radar, no doubt contributed to the development radio astronomy as a viable field of experimental research. home.earthlink.net /~jcmannone/id3.html   (1710 words)

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