It is widely accepted that cometary nu-
clei are composed of a mix of volatile ices and meteor-
itic materials. In a series of seminal papers F. L.
Whipple tried to explain how the irregular internal
structure of each nuclei would be able to explain the
nongravitational forces, and how the continuous sub-
limation of the ice species would lead to explain the
origin of meteoroid streams [1,2,3]. Not essential pro-
gress was made until that the approach of a cruise of
international spacecrafts to comet 1P/Halley allowed to
achieve the first direct view of a cometary nucleus [4].
At that time several models were built to explain the
main features observed in 1P/Halley nucleus under the
main concept that cometary nuclei were born from the
accretion of weakly bounded ice-rich cometesimals [5,
6]. A similar view was extracted from the 81P/Wild 2
fragile aggregates recovered by Stardust mission [7].
Obviously, particles recollected in the coma of a comet
are biased towards those fragile aggregates that are
lifted off from ice-rich regions by the sublimated gas
drag. Many cometary meteoroid streams crossing the
Earth were formed in this way, but not all. Catastro-
phic disruption of cometary nuclei is also a regular
mechanism of producing meteoroid streams [8, 9, 10].
Interestingly, this mechanism is able to produce large
boulders as observed e.g. during the disruption of
comet C/1999 S4 LINEAR [11]. It was believed that
the large fragments released by these break-up events
will proceed to faint in the coma due to suffer a cas-
cade fragmentation. Obviously remote observations
are not able to decipher if the final product of these
events are mm- or m-sized meteoroids. In a recent pa-
per [12] we identified a meter-sized meteoroid that
was probably produced during the disintegration of
comet C1919Q2 Metcalf. It produced a
very bright
fireball, with a maximum brightness of magn. –18 that
was observed over much of Spain as well as parts of
Portugal, and France on July 11, 2008 at 21:17:39
UTC. Fortuitously, it flew over many of the instru-
ments operated by the SPanish Meteor and Fireball
Network (SPMN) so that accurate measurements of its
properties were recorded. Here we summarize both
these observations and the deductions made from them
regarding the nature and origin of the body that gave
rise to this fireball.
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