Twinkling, also called scintillation, is a generic term for variations in apparent brightness, colour, or position of a distant luminous object viewed through a medium.[1] If the object lies outside the Earth's atmosphere, as in the case of stars and planets, the phenomenon is termed astronomical scintillation; for objects within the atmosphere, the phenomenon is termed terrestrial scintillation.[2] As one of the three principal factors governing astronomical seeing (the others being light pollution and cloud cover), atmospheric scintillation is defined as variations in illuminance only.
In simple terms, twinkling of stars is caused by the passing of light through different layers of a turbulent atmosphere. Most scintillation effects are caused by anomalous atmospheric refraction caused by small-scale fluctuations in air density usually related to temperature gradients.[3][4] Scintillation effects are always much more pronounced near the horizon than near the zenith (directly overhead),[5] since light rays near the horizon must penetrate a denser layer of and have longer paths through the atmosphere before reaching the observer. Atmospheric twinkling is measured quantitatively using a scintillometer.[6] The effects of twinkling are reduced by using a larger receiver aperture; this effect is known as aperture averaging.[7][8]
While light from stars and other astronomical objects is likely to twinkle,[9] twinkling usually does not cause images of planets to flicker appreciably.[10][11] Stars twinkle because they are so far from Earth that they appear as point sources of light easily disturbed by Earth's atmospheric turbulence, which acts like lenses and prisms diverting the light's path. Large astronomical objects closer to Earth, like the Moon and other planets, encompass many points in space and can be resolved as objects with observable diameters. With multiple observed points of light traversing the atmosphere, their light's deviations average out and the viewer perceives less variation in light coming from them.[12][13]
See alsoedit
Look up scintillate or twinkle in Wiktionary, the free dictionary.
^Sofieva, V. F.; Dalaudier, F.; Vernin, J. (2013-01-13). "Using stellar scintillation for studies of turbulence in the Earth's atmosphere". Philosophical Transactions of the Royal Society. 371 (1982). The Royal Society: 20120174. doi:10.1098/rsta.2012.0174. ISSN 1364-503X.
^Chun, M.; Avila, R; "Turbulence profiling using a scanning scintillometer", Astronomical Site Evaluation in the Visible and Radio Range, Astronomical Society of the Pacific 266:72–78.
^Perlot, N.; Fritzsche, D. "Aperture-Averaging – Theory and Measurements", elib – Electronic Library.
^Andrews, C.; Phillips, R. L.; Hopen, C. (2000). "Aperture averaging of optical scintillations". Waves in Random Media. 10 (1). Taylor & Francis: 53–70. doi:10.1088/0959-7174/10/1/305. S2CID 120797868.
^Wheelon, Albert D. (2003). Electromagnetic Scintillation: Volume 2, Weak Scattering. Cambridge University Press. ISBN978-1-139-43960-2.
^Kenyon, S. L.; Lawrence, M. et al; "Atmospheric Scintillation at Dome C, Antarctica", Astronomical Society of the Pacific118, 924–932.
^Ellison, M. W. (1952). "Why do Stars Twinkle?". Irish Astronomical Journal. 2 (1): 5–8. Bibcode:1952IrAJ....2....5E.
^Graham, John A. "Why do stars twinkle?" Scientific American, October 2005.
^Byrd, Deborah; "Why don’t planets twinkle as stars do?", Earthsky, October 24, 2005.
January 01, 1970
twinkling, other, uses, twinkle, disambiguation, scintillation, also, called, scintillation, generic, term, variations, apparent, brightness, colour, position, distant, luminous, object, viewed, through, medium, object, lies, outside, earth, atmosphere, case, . For other uses see Twinkle disambiguation and Scintillation Twinkling also called scintillation is a generic term for variations in apparent brightness colour or position of a distant luminous object viewed through a medium 1 If the object lies outside the Earth s atmosphere as in the case of stars and planets the phenomenon is termed astronomical scintillation for objects within the atmosphere the phenomenon is termed terrestrial scintillation 2 As one of the three principal factors governing astronomical seeing the others being light pollution and cloud cover atmospheric scintillation is defined as variations in illuminance only source source source source source source The twinkling of the brightest star in the night sky Sirius apparent magnitude of 1 1 shortly before upper culmination at the meridian at 20 above the southern horizon In 29 seconds Sirius appears to move 7 5 arcminutes from left to right In simple terms twinkling of stars is caused by the passing of light through different layers of a turbulent atmosphere Most scintillation effects are caused by anomalous atmospheric refraction caused by small scale fluctuations in air density usually related to temperature gradients 3 4 Scintillation effects are always much more pronounced near the horizon than near the zenith directly overhead 5 since light rays near the horizon must penetrate a denser layer of and have longer paths through the atmosphere before reaching the observer Atmospheric twinkling is measured quantitatively using a scintillometer 6 The effects of twinkling are reduced by using a larger receiver aperture this effect is known as aperture averaging 7 8 While light from stars and other astronomical objects is likely to twinkle 9 twinkling usually does not cause images of planets to flicker appreciably 10 11 Stars twinkle because they are so far from Earth that they appear as point sources of light easily disturbed by Earth s atmospheric turbulence which acts like lenses and prisms diverting the light s path Large astronomical objects closer to Earth like the Moon and other planets encompass many points in space and can be resolved as objects with observable diameters With multiple observed points of light traversing the atmosphere their light s deviations average out and the viewer perceives less variation in light coming from them 12 13 See also edit nbsp Look up scintillate or twinkle in Wiktionary the free dictionary Adaptive optics Interplanetary scintillation Observational astronomy Twinkle Twinkle Little Star Twelve Variations on Ah vous dirai je Maman References edit Wang Ting I Williams Donn Scintillation technology bests NIST Archived 2013 10 04 at the Wayback Machine InTech May 1 2005 NASA Aerospace Science and Technology Dictionary NASA gov Sofieva V F Dalaudier F Vernin J 2013 01 13 Using stellar scintillation for studies of turbulence in the Earth s atmosphere Philosophical Transactions of the Royal Society 371 1982 The Royal Society 20120174 doi 10 1098 rsta 2012 0174 ISSN 1364 503X VanCleave Janice Stellar Scintillation Twinkling Stars JVC s Science Fair Projects May 2 2010 Scintillation or Atmospheric Boil noaa gov Chun M Avila R Turbulence profiling using a scanning scintillometer Astronomical Site Evaluation in the Visible and Radio Range Astronomical Society of the Pacific 266 72 78 Perlot N Fritzsche D Aperture Averaging Theory and Measurements elib Electronic Library Andrews C Phillips R L Hopen C 2000 Aperture averaging of optical scintillations Waves in Random Media 10 1 Taylor amp Francis 53 70 doi 10 1088 0959 7174 10 1 305 S2CID 120797868 Wheelon Albert D 2003 Electromagnetic Scintillation Volume 2 Weak Scattering Cambridge University Press ISBN 978 1 139 43960 2 Kenyon S L Lawrence M et al Atmospheric Scintillation at Dome C Antarctica Astronomical Society of the Pacific 118 924 932 Ellison M W 1952 Why do Stars Twinkle Irish Astronomical Journal 2 1 5 8 Bibcode 1952IrAJ 2 5E Graham John A Why do stars twinkle Scientific American October 2005 Byrd Deborah Why don t planets twinkle as stars do Earthsky October 24 2005 Retrieved from https en wikipedia org w index php title Twinkling amp oldid 1210848007, wikipedia, wiki, book, books, library,
