Red-orange tongues of fire blaze from its mouth like a flame-thrower. Witnesses recount seeing one (or several) green (or orange-red) serpents writhing in the sky. Others describe a long, serpentine body with leathery bat-like wings and multiple heads each disgorging fire. As the monster flies across the sky, a loud hissing is heard and smoking-hot scales rain down. Accounts such as these abound in ancient literature and are reflected in the art of all cultures. Nearly identical language, accompanied by photos, can be found in today's professional meteoritic journals describing the explosion of fireballs entering the earth's atmosphere. Such explosions create long-lingering smoke trains of hot, ionized gas that change spectral colors and shape over time as wind in the upper atmosphere twists them about (see photo below). Do dragon myths embody distant folk-memories of meteor events? The dragons portrayed in traditional Chinese art suggest such events as they seem to twist and hover like vapor-clouds trailing behind their fireballs. Like the ancients, scientists today struggle to find explanations for the baffling meteoritic phenomenon they observe.
Related Record from CAplus
141: 210310 A "shocking" Leonid meteor at 1000 fps. Stenbaek-Nielsen, Hans C.; Jenniskens, Peter. Geophysical Institute, University of Alaska, Fairbanks, AK, USA. Advances in Space Research 2004, 33(9), 1459-1465 (Eng). A bright, estd. Magnitude -3, Leonid meteor was obsd. from the University of Alaska Fairbanks Poker Flat Research Range north of Fairbanks, Alaska, at 10:42 UT on 18 Nov. 2001. Images of the meteor were recorded at 1000 frames per s. The millisecond time resoln. allows spatial structures in the ablation cloud to be recorded without smearing due to the ~72 km/s Leonid entry velocity. The meteor was first obsd. at an altitude of about 123 km. As it descended deeper into the atm. it brightened and a tail developed. In addn., a bright structure developed in front of the meteor, much resembling a shock, reaching its max. brightness at an altitude of 104 km. The spatial scale-size of the shock-like structure is large, several 100 m. Observation of such structure has, to our knowledge, not been reported before. We do not have an explanation for its cause. If its formation is similar to the shock obsd. around re-entry vehicles it would indicate the size of the meteor to be ~100 m, which is clearly not realistic. The meteor will create ionization, but at 105 km the ion mean-free path is only ~1 m and it is difficult to see how ionospheric plasma instabilities driven by the ionization caused by the meteor can result in ~100 m structures. It is more likely that the structure is assocd. with photochem. processes driven by the intense UV radiation from the hot meteor. A simple computer simulation appears to be able to reproduce the observations. However, the process cannot just be photo ionization of the ambient mol. oxygen or nitrogen as the required total photon flux is too large to be energetically possible.
132: 38381 Coordinated observations of two large Leonid meteor fireballs over northern New Mexico, and computer model comparisons. Zinn, J.; Wren, J.; Whitaker, R.; Szymanski, J.; ReVelle, D. O.; Priedhorsky, W.; Hills, J.; Gisler, G.; Fletcher, S.; Casperson, D.; Bloch, J.; Balsano, R.; Armstrong, W. T.; Akerlof, C.; Kehoe, R.; McKay, T.; Lee, B.; Kelley, M. C.; Spalding, R. E.; Marshall, S. Los Alamos National Laboratory, NM, USA. Meteoritics & Planetary Science 1999, 34(6), 1007-1015 (Eng). This paper describes the coordinated results of several sets of measurements of two Leonid meteor fireballs over northern New Mexico at 1:32 and 3:06 MST, resp., on the night of 1998 Nov. 17. The measurements included visible band photometry on both events, as well as filtered 5890 all-sky images of the Na airglow. Also, for the 3:06 A.M. event, we obtained an infrasound measurement of the hydrodynamic yield. For the 1:32 A.M. event, we obtained a set of visible band charge-coupled device (CCD) camera images of the meteor train for times extending to 30 min after the initial impact. The measurement results have been combined to derive an optical efficiency for the intense early-time optical flash, and the total explosion yields and masses for both of the meteors. We have also done a set of numerical radiation, hydrodynamic, and chem. computations to investigate the nature and distribution of the long-lasting airglow. We attribute the brightest visible airglow to at. O 5577 line emission, with addnl. contributions from at. Na emission and NO2 chemiluminescence. The near-IR atm. bands of mol. O2 should be very strong as well. All of the band emissions are expected to show a hollow limb-brightened structure.
Additional Information
Updated: 1/27/2009 10:22:56 AM
