Open AccessExtreme albedo comets and the impact hazard
Author(s) -
Napier W. M.,
Wickramasinghe J. T.,
Wickramasinghe N. C.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.08309.x
Subject(s) - zodiacal light , physics , meteoroid , astrobiology , astronomy , asteroid , comet , albedo (alchemy) , comet dust , population , solar system , debris , near earth object , astrophysics , interplanetary dust cloud , meteorology , history , demography , sociology , performance art , art history
Dynamical balance arguments that involve the capture of long‐period comets from the Oort cloud imply that there should be ∼ 1000 times more Halley‐type objects than are actually observed. If the active comets rapidly become dormant, with albedos comparable to those of known cometary surfaces, hundreds of such bodies should by now have been detected whereas in fact only a few have been found. If, on the other hand, they disintegrate to dust, we show here that the debris would create a bright, near‐spherical zodiacal cloud and ∼ 15–30 strong annual meteor showers, also contrary to observation. Here we demonstrate that the surfaces of inactive comets, if composed of loose, fluffy organic material like cometary meteoroids, develop reflectivities that are vanishingly small in visible light. The near‐Earth objects may therefore be dominated by a population of fast, multi‐kilometre bodies too dark to be seen with current near‐Earth object surveys. Deflection strategies that assume decades or centuries of warning before impact are inapplicable to this hazard.