Radiation astronomy/Particles

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The image shows the first film ever of a meteor plunging down at terminal velocity. Credit: Anders Helstrup / Dark Flight, montage, Hans Erik Foss Amundsen.

"A skydiver may have captured the first film ever of a meteorite plunging down at terminal velocity, also known as its “dark flight” stage."[1]

"The footage was captured in 2012 by a helmet cam worn by Anders Helstrup as he and other members of the Oslo Parachute Club jumped from a small plane that took off from an airport in Hedmark, Norway."[1]

“It can’t be anything else. The shape is typical of meteorites -- a fresh fracture surface on one side, while the other side is rounded.”[2]

“It has never happened before that a meteorite has been filmed during dark flight; this is the first time in world history.”[2]

"Having the rock in hand would certainly help. But despite triangulations and analyses, Helstrup and his recruits still haven’t found it."[1]


Def. the solid material thrown into the air by a volcanic eruption that settles on the surrounding areas is called tephra.

"[T]ephra, is a general term for fragments of volcanic rock and lava that are blasted into the air by volcanic explosions or carried upward in the volcanic plume by hot, hazardous gases. The larger fragments usually fall close to the volcano, but the finer particles can be advected quite some distance. ... [Fine ash] can contain rock, minerals, and volcanic glass fragments smaller than .1 inch in diameter, or slightly larger than the size of a pinhead."[3]


Def. a suspension of dry dust in the atmosphere is called a lithometeor.

"A lithometeor consists of solid particles suspended in the air or lifted by the wind from the ground."[4]

"A lithometeor is the general term for particles suspended in a dry atmosphere; these include dry haze, smoke, dust, and sand."[3]

"Dry haze is an accumulation of very fine dust or salt particles in the atmosphere; it does not block light, but instead causes light rays to scatter. Dry haze particles produce a bluish color when viewed against a dark background, but look yellowish when viewed against a lighter background. This light-scattering phenomenon (called Mie scattering) also causes the visual ranges within a uniformly dense layer of haze to vary depending on whether the observer is looking into the sun or away from it."[3]

Heavy metal pollution may occur in lithometeors.[5]

"The rise of airborne dust is constantly augmenting from the desert (Bilma) to the southern Sahelian stations (Niamey) where it has increased by a factor five. ... the Sahelian zone with airborne dust during the 80s ... All stations have recorded a general increase of wind velocity. The increase of lithometeors frequency as well as the wind velocity during the drought period is not explained by the aridification."[6]

Photographic meteors[edit]

"The distribution of photographic meteors in iron, stony, and porous meteors is given in this paper".[7] "[A]mong all the 217 meteors for which we know the beginning there are 70 iron meteors, i. e. about 32 p. c., and 147 stony meteors, i. e. 68 p. c."[7] The meteor streams: Perseids, Geminids, Taurids, Lyrids, κ Cygnids and Virginids, are quite stony.[7]

"The dominant group in all cases are stony meteors."[7]

Wentworth scales[edit]

These are pebbles on a beach. Credit: Slomox.
This image shows a rock apparently where it fell. Credit: Sten Porse.

Most meteoroids that cause meteors are about the size of a pebble.

Def. a particle classification system based on diameter is called the Wentworth scale.

Def. a particle less than 1 micron in diameter is called a colloid.

Def. a particle less than 3.9 microns in diameter is called a clay.

Def. a particle from 3.9 to 62.5 microns in diameter is called a silt.

Def. a particle less than 62.5 microns in diameter is called a mud.

Def. a particle from 62.5 microns to 2 mm in diameter is called a sand.

Def. a particle from 2 to 64 mm in diameter is called a gravel.

Def. a particle from 2 to 4 mm in diameter is called a granule.

Def.' a particle from 4 to 64 mm in diameter is called a pebble.

Def. a particle from 64 to 256 mm in diameter is called a cobble.

Def. a particle [or large piece of stone greater than 256 mm in diameter that can theoretically be moved if enough force is applied is called a boulder.


The Comprehensive Suprathermal and Energetic Particle Analyzer (COSTEP) aboard SOHO "detects and classifies very energetic particle populations of solar, interplanetary, and galactic origin."[8]

See also[edit]


  1. 1.0 1.1 1.2 Janet Fang (April 4, 2014). Skydiver Almost Hit by Meteorite. IFLScience. Retrieved 2014-08-31.
  2. 2.0 2.1 Hans Erik Foss Amundsen (April 4, 2014). Skydiver Almost Hit by Meteorite. IFLScience. Retrieved 2014-08-31.
  3. 3.0 3.1 3.2 Mark R. Mireles, Kirth L. Pederson, Charles H. Elford (February 21, 2007). Meteorologial Techniques. 106 Peacekeeper Drive, Suite 2N3, Offutt Air Force Base, Nebraska USA: Air Force Weather Agency/DNT. Retrieved 2013-02-17.CS1 maint: Multiple names: authors list (link)
  4. PJ Ozer (1995). Fantechi, R.;Peter, D.;Balabanis, P.;Rubio, J. L.. ed. Lithometeors in relation with desertification in the Sahelian area of Niger, In: Desertification in a European context: physical and socio-economic aspects. Luxembourg: Office for Official Publications of the European Community. pp. 567-74. ISBN 92-827-4163-X. http://www.cabdirect.org/abstracts/19971901329.html. Retrieved 2013-02-17. 
  5. Jian-qiao Yu, Xia1 Wang, Li Wen, Jing-shun Wang (April 2008). "Studies on Correlation of Heavy Metal Pollution in Soil, Lithometeor". Journal of Agricultural Science and Technology (04). http://en.cnki.com.cn/Article_en/CJFDTOTAL-NKDB200804025.htm. Retrieved 2013-02-17. 
  6. P. Ozer (1998). G. Demaree, J. Alexandre, M. de Dapper, ed. Lithometeors and wind velocity in relation with desertification during the dry season from 1951 to 1994 in Niger, In: International Conference on tropical climatology, meteorology and hydrology in memoriam Franz Bultot. Bruxelles (Belgium): Royal Meteorological Institute of Belgium; Royal Academy of Overseas Sciences. pp. 212–27. Retrieved 2013-02-17.CS1 maint: Multiple names: editors list (link)
  7. 7.0 7.1 7.2 7.3 Zd. Ceplecha (1958). "On the composition of meteors". Bulletin of the Astronomical Institutes of Czechoslovakia 9: 154-9. 
  8. B. Heber (30 June 2003). SOHO Fact Sheet (PDF). Greenbelt, MD 20771, USA: NASA/GSFC. Retrieved 2016-03-27.

External links[edit]