Free Astronomy Magazine November-December 2014

SMALL BODIES article recently pu- blished in Astro- nomy & Astrophys- ics , is not anyhow about the possible location of the larg- er fragments, but rather concerns the trajectory followed in the atmosphere by the small-mass ones, more subject to wind action and hence less easy to pinpoint on the ground. The chances of recovering these type of objects are theoretically much higher, since cur- rent models indi- cate that a meteor- oid such as that exploded over Benešov, 1-2 metres wide and weighing about 4 tons, can produce 250,000 fragments rang- ing from 1 to 10 grams and of these about 40,000 weighing more than 5 grams. To understand how and to what extent air masses may have affected the fall of frag- ments of that size, the researchers have drawn from the meteorological archives detailed information on wind profile from this has direct consequences on determin- ing the location where the larger frag- ments may have touched the ground; location that the new calculations set at nearly 400 metres away from that previous- ly estimated, once again on a terrain that in the ‘90s was particularly rugged. The most interesting aspect of the reinter- pretation of the Benešov bolide, well evi- denced by Spurný, Borovi č ka et al. in an O n this map are shown, in projection, the new trajectory of the bolide, the point of the ex- plosion at an alti- tude of 24.4 km and, in the top right, the area 2.5 km away where the 5-10 grams fragments fell after following the paths synthe- sized in the small graph. Right, de- tailed image of the cultivated field where the Czechs re- searchers recov- ered the only four known frag- ments of the Be- nešov meteorite. All are well with- in the area pre- dicted by the calculations. [Spurný et al.]