Bolide (Meteor)

from Wikipedia, the free encyclopedia

A particularly bright meteor is referred to as a bolide (e) , fireball or fireball . Meteors are caused by the penetration of meteoroids into the earth's atmosphere .

In contrast to the less bright falling stars , which are only the size of dust grains (from about 0.1 mm in size), they are more massive bodies (over 1 cm), which can sometimes fall on the earth's surface as meteorites .

Definition of terms

The term is mostly used for meteors whose apparent brightness is greater than that of the brightest planet, Venus , i.e. greater than −4 mag . Weaker events are known as shooting stars. Occasionally, a particularly bright event that is brighter than about −17 mag, that is about 100 times brighter than the full moon , is called superbolide . However, both boundaries are not sharp.

event

While the glowing trace ( ionization of the air) of most meteors ends above 60 kilometers in altitude, larger meteoroids can reach lower final heights (around 20 km) with slower entry (below about 25 km / s) and solid material. This then increases the likelihood that material will fall onto the earth's surface as a meteorite . A meteorite fall is not the rule even with very bright fireballs.

Brightness development

The brightness of a meteor is determined by its mass, but even more strongly by its speed of entry into the earth's atmosphere. The ionization of the atmosphere and the ablation of the penetrating material per unit of time determine the brightness of the meteor. If a lot of material is suddenly removed from the meteoroid per second, the meteor becomes significantly brighter, but the intruder now also loses mass much faster. For this reason, it often happens that meteoroids made of soft, rather loose material (e.g. cometary objects) explode in a spectacular fireball in a very short time (about 2 s) and other, more solid materials (e.g. stony objects) ) are consumed in a much longer flight phase (about 6 s) in the form of a less spectacular fireball, although both meteoroids otherwise had the same initial conditions (entry speed and mass). The less ablation the penetrating bullet shows, the higher the chance of a residual mass that can reach the ground.

Fragmentation

Fig. A) shows a meteor event known as a fireball or bolide. You can see the two phases of the plasma  - the impact front plasma is turquoise and the plasma tail orange. Fig. B) shows the already disintegrated meteoroid in the last visible phase of the fall as a bolide or fireball

Objects with a large initial mass will penetrate deep into the earth's atmosphere (e.g. 20 km). Since the air density increases sharply in the direction of the earth's surface, the effect on the object becomes more and more intense. The meteoroid is getting smaller and weaker at the same time. A situation arises in which the forces of the atmosphere become too great for the material to penetrate. A break at inhomogeneities in the material becomes likely and the body fragments. As a rule, there is an outbreak of brightness. Even a normal meteor can become a ball of fire or a bolide at this moment.

With the fragmentation and the suddenly enlarged surface, there is also a much higher rate of ablation, which determines the light production and thus that light outbreak occurs in the first place. The highly compressed gases (or the plasma) now also flow away between the newly created fragments and experience much less resistance than just before, when the object still existed as a whole. The compressed gas can expand suddenly and drives the meteorite pieces apart. If these fragments survive the further fall, a meteor shower occurs.

Meteorite fall (perception)

When the weather conditions are suitable, the perception of a meteorite fall begins with a spectacular light phenomenon. Usually nothing can be seen during the day or when it is cloudy. After such a fireball or bolide event can a short time later to the perception of a sound phenomenon ( sonic boom ) come when the meteorite crashes with multiple speed of sound through the increasingly dense atmosphere. Depending on the position of the observer in relation to the flight path and depending on its course, there may be a short bang, but the sound intensity can also increase and decrease again. Depending on the distance of the observer to the flight path, size and speed of the meteorite, the thunder can follow quickly and be very loud or it can only arrive at the observation site several minutes later as a dull rumble of thunder. If the distance to the flight path is too great or if the acoustic conditions are unsuitable (background noise, noise protection), the sound event may not be perceived.

Known events

Name / place date Meteorite fall Magnitude
Ensisheim meteorite 0Nov 7, 1492 Traces of light, loud thunder, several eyewitnesses, find weighing over 100 kilograms
Fireball in front of New Caledonia  Sep 1774 "Fireball that resembled the sun in size and shine, but was somewhat paler in light"
Pultusk (Poland) Jan. 30, 1868 With 68,780 fragments found, it is the largest meteor shower ever observed
Meteorite Bjurböle (Finland) March 12 1899 At least 330 kilograms
Tunguska event - impact hypothesis June 30, 1909 Course not clear
"Meteor of Oldenburg" ( Oldenburg ) Sep 10 1930 Oldenburg −14 likes
Sikhote-Alin (Russia) Feb 12, 1947 More than 120 craters and over 8000 meteorite fragments
Meteorite Abee (Canada) 0June 9, 1952 Largest known enstatite chondrite (at least 107 kilograms)
Meteorite Přibram (Bohemia) 0Apr 7, 1959 first meteorite found with meteor cameras
Meteorite Allende (Mexico) 0Feb. 8, 1969 Bright fireball, shower with numerous fragments
Fireball August 10, 1972 (North America) Aug 10, 1972 Has penetrated the atmosphere, but has not landed on the ground, has left the earth again with reduced speed and mass
Peekskill meteor 0Oct 9, 1992 Peekskill −12.8 mag
Lugo -Bolide Jan. 19, 1993   −23 likes
Tagish Lake Fireball Jan. 18, 2000 Tagish Lake −22 likes
"Meteor of Bavaria" ( Neuschwanstein ) 0Apr 6, 2002 Neuschwanstein −17 likes
Meteor over the Mediterranean (2002) 0June 6, 2002
Day bolide from León 0Jan. 4, 2004 Villalbeto de la Peña −18 likes
Carancas (Peru) Sep 15 2007 At 11:45 a.m. local time, the bolide struck a crater almost 14 m in diameter, vapors caused nausea and headaches brighter than the sun
2008 TC3 (Sudan) 0Oct 7, 2008 First asteroid that was observed before entering the earth's atmosphere. Found meteorites are called "Almahata Sitta"
" Baltic Sea Bolide" Jan. 17, 2009 Maribo −19 likes
Ash Creek, Texas Feb 15, 2009 Video camera record, at least 11 kilograms
Fireball Sulawesi 2009 , Watampone , Sulawesi , Indonesia 0Oct 8, 2009 03:00 UTC
Fire meteor from October 13th 2009 , Netherlands , Germany , North Sea coast Oct 13, 2009 No meteorites found so far
Bolide over central Germany 17th Mar 2012 Direction of flight from east to west, probably burned up over southern Thuringia (sighted from Dresden, Berlin, Jena, Würzburg)
Sutter's Mill bolide over Coloma , California , United States Apr 22, 2012 Fragments of a meteorite weighing several tons in Coloma (district of Lotus)
Bolide from September 21, 2012 , Northern and Central Europe, possibly North America 21 Sep 2012 Still unclear
Chelyabinsk Meteor , Chelyabinsk ( Urals ) Feb 15, 2013 Traces of light, loud thunders, explosions and a wake of smoke, pressure waves, the decline of fragments, almost 1,500 injured people and property damage <  −26 mag
Bolide from March 15, 2015,
Southern Germany - Switzerland		 15th Mar 2015 Still unclear [1]
Fireball over Belgium June 16, 2018 Still unclear [2]
Daylight fireball from September 12, 2019,
Schleswig-Holstein		 Sep 12 2019 Flensburg 24.5 g
Daylight fireball from April 6, 2020,
Germany / Austria		 0Apr 8, 2020 13:32 UTC Still unclear (area of ​​the Berchtesgaden National Park - Hallein (originally: Hallein - Mondsee - Attersee )) Sightings from: DACH, I, SLO.

See also

literature

  • Alfred Wegener: The detonating meteor from April 3, 1916 in Kurhessen. NG Elwert Verlag, Marburg 2001, ISBN 3-7708-1160-7 .
  • Dieter Heinlein: The fireball from April 6, 2002 and the sensational meteorite fall "Neuschwanstein". Edited by Dieter Heinlein. Augsburg 2004.
  • Joachim Herrmann: Dictionary of Astronomy. Deutscher Taschenbuch-Verlag, Munich 1996, ISBN 3-423-03362-2 .
  • Lexicon of Astronomy. Spektrum Akademischer Verlag, Heidelberg 1995, ISBN 3-86150-145-7 .

Web links

Individual evidence

  1. ^ "Super-Meteor" Lights up Northern Sky . On: yle.fi
  2. ↑ a b Z. Ceplecha, RE Spalding, C. Jacobs, DO Revelle, E. Tagliaferri, P. Brown: Super Bolides . In: Meteoroids 1998 . WJ Baggaley and V. Porubcan (eds.), Astronomical Institute Slovak Academy of Sciences, Bratislava 1999, pp. 37-54
  3. ↑ Georg Forster : Journey around the world . tape 2 , 1780, p. 345 ( online ).
  4. ↑ P. Brown et al. : The orbit and atmospheric trajectory of the Peekskill meteorite from video records . In: Nature . tape 367 , 1994, p 624–626 , doi : 10.1038 / 367624a0 ( online [PDF; 2.9 MB ]).
  5. ^ Lugo bolide
  6. ↑ P. Brown, DO ReVelle, AR Hildebrand: The Tagish Lake Meteorite Fall: Interpretation of fireball physical characteristics (PDF; 8.4 MB).
  7. ↑ Jordi Llorca, Josep M. Trigo-Rodrõguez, José L. Ortiz, Josè A. Docobo, Javier Garcõa-Guinea, Alberto J. Castro-Tirado, Alan E. Rubin, Otto Eugster, Wayne Edwards, Matthias Laubenstein, and Ignasi Casanova : The Villalbeto de la Peña meteorite fall: I. Fireball energy, meteorite recovery, strewn field, and petrography .
  8. ↑ Detonating bolide over the Baltic Sea
  9. ↑ Asteroid Impactor Reported over Indonesia . NASA . October 23, 2009. Archived from the original on November 2, 2009.
  10. ↑ Asteroid explosion over Indonesia raises fears about Earth's defenses . In: The Telegraph . October 27, 2009. Archived from the original on October 29, 2009.
  11. ↑ Asteroid explosion was a whopper for Earth . In: NBC News . October 29, 2009. Archived from the original on August 25, 2013.
  12. ↑ Huge Explosion Was Biggest Space Rock to Strike Earth Since 1994 . In: Space.com . October 29, 2009. Archived from the original on January 30, 2011.
  13. ↑ Amateur video footage . YouTube . Archived from the original on October 31, 2010.
  14. ↑ Matthias Rückemann: Astrotreff - Astronomy Meeting point - meteor. In: www.astrotreff.de. Retrieved April 18, 2016 .
  15. ↑ Bolide over Berlin March 17th, 2012 7:30 p.m. - AKM eV Forum. In: forum.meteoros.de. Retrieved April 18, 2016 .
  16. ↑ Meteorites found in Coloma-Lotus likely from giant fireball over weekend
  17. ↑ Meteorite Pieces Found in Coloma, Lotus  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. , FOX40.com - Chris Biele reports on Apr 25, 2012@1@ 2Template: Dead Link / www.fox40.com  
  18. ↑ NASA Jet Propulsion Laboratory: Russia Meteor Not Linked to Asteroid Flyby.
  19. ↑ event / 2020/1591 fireball.amsmeteors.org, April 6, 2020, forum constantly updated, accessed April 10, 2020.– Report of a stone find in Pfaffenhofen in Saalfelden am Steinernen Meer , A. Lists 852 sighting reports by April 10, 12.00 CEST .
  20. ↑ Universe: Video shows fireball over Austria orf.at, April 8, 2020, accessed April 9, 2020.
  21. ↑ Meteorite: Numerous Sightings orf.at, April 7, 2020, accessed April 10, 2020.
  22. ↑ Fireball over the Attersee nachrichten.at, April 7, 2020, accessed April 9, 2020. - Map of the places with sightings. Video.