Search

The materials of large asteroids and asteroid families are sampled by meteorites that fall to Earth. The cosmic ray exposure age of the meteorite identifies the collision event from which that meteorite originated. The inclination of the orbit on which the meteoroid impacted Earth measures the inclination of the source region, while the semi-major axis of the orbit points to the delivery resonance, but only in a statistical sense. To isolate the sources of our meteorites requires multiple documented falls for each cosmic ray exposure peak. So far, only 36 meteorites have been recovered from observed falls. Despite these low numbers, some patterns are emerging that suggest CM chondrites originated from near the 3:1 resonance from a low-inclined source (perhaps the Sulamitis family), LL chondrites came to us from the ν6 resonance (perhaps the Flora family), there is an H chondrite source at high inclination (Phocaea?), and one group of low shock-stage L chondrites originates from the inner main belt. Other possible links are discussed. [ABSTRACT FROM AUTHOR]

Some main-belt asteroids evolve into near-Earth objects. They can then experience the same meteoroid-producing phenomena as active asteroids in the main belt. If so, they would produce meteoroid streams, some of which evolve to intersect Earth's orbit and produce meteor showers at Earth. Only few of those are known. Meteoroid streams that move in orbits with Tisserand parameter well in excess of 3 are the Geminids and Daytime Sextantids of the Phaethon complex and the lesser known epsilon Pegasids. The observed activity appears to be related to nearly whole scale disintegrations, rather than dust ejection from volatile outgassing as observed in active comets. There is only a small population of asteroids with a main-belt origin that recently disintegrated into meteoroid streams. [ABSTRACT FROM PUBLISHER]

The business meeting of commission 22 was held at the room 403 on 24 th August 2012 (14:00-15:30) in the China National Convention Center in Beijing. [ABSTRACT FROM AUTHOR]

The first asteroid to be discovered in space and subsequently observed to impact Earth, asteroid 2008 TC3, exploded at a high 37 km altitude and stopped ablating at 32 km. This would classify the fireball as of Ceplecha's PE-criterion IIIb/a, meaning “cometary” in nature. In this case, the structural weakness may have come from pores found in some of the recovered meteorites, called “Almahata Sitta” (= Station 6 in Arabic). The explosion turned most of the asteroid mass to dust and vapor, only a tiny fraction shattered into macroscopic meteorites, the heaviest of which was 283 gram. Other similarly frail asteroids may be related to main belt comets. [ABSTRACT FROM PUBLISHER]

Commission 22 is part of Division III on Planetary System Sciences of the International Astronomical Union. Members of Commission 22 are professional scientists studying bodies in the Solar System smaller than asteroids and comets, and their interactions with planets. The main subjects of interest are meteors, meteoroids, meteoroid streams, interplanetary dust particles, and also zodiacal cloud, meteor trains, meteorites, tektites, etc. [ABSTRACT FROM PUBLISHER]

Many of our annual showers do not have active parent comets. In recent years, minor planets have been identified that move among the meteoroids streams. Some streams, such as the Quadrantids, Geminids, and Sextantids, are in such unusual orbits that the probability of a chance association is only of order 1 in 106. The streams identify those objects as dormant comet nuclei. Other streams, such as the Phoenicids and α-Capricornids are associated with minor planets that were found to be weakly active at their last perihelion passage. All the streams investigated so far are young, less than 2,000 years old, and can not have been created in the classical sense of meteoroids being ejected from the comet nucleus by water vapor drag. Instead, these (mostly) dormant comets lost fragments at some point in the past, which crumbled into meteoroid streams. Scars of such events are now identified on the surface of active Jupiter family comets 9P/Tempel 1 and 81P/Wild 2. Thus, the meteor showers on Earth bear witness to what is the dominant mass-loss mechanism of comets in the inner solar system, a process that can account for much of the zodiacal cloud dust and the zodiacal dust bands. [ABSTRACT FROM PUBLISHER]

The business meeting of commission 22 was held at the room 5 in the SulAmerica Convention Center in Rio de Janeiro(14:00-15:30). Fifteen people attended at this meeting:J.Borovička, E.Bowell, G.Consolmagno, D.Green, P. Jenniskens, A. Pellinen-Wannberg, R. Rudawska, J. Watanabe, J. Zhu, P. H. A. Hasselmann, F. Ostroviski, D. A. Oszkiewicz, W. Thuillot, P. Mahajani, and A. Sule. This meeting was managed by Junichi Watanabe, the current C22 Vice-President. The summary of the meeting is described. [ABSTRACT FROM PUBLISHER]

The business meeting of commission 22 was held at the room 5 in the SulAmerica Convention Center in Rio de Janeiro(14:00-15:30). Fifteen people attended at this meeting:J.Borovička, E.Bowell, G.Consolmagno, D.Green, P. Jenniskens, A. Pellinen-Wannberg, R. Rudawska, J. Watanabe, J. Zhu, P. H. A. Hasselmann, F. Ostroviski, D. A. Oszkiewicz, W. Thuillot, P. Mahajani, and A. Sule. This meeting was managed by Junichi Watanabe, the current C22 Vice-President. The summary of the meeting is described. [ABSTRACT FROM PUBLISHER]

Present were the members Abe, Babadzhanov, Baggaley, Borovička, Bowell, Ceplecha, Consolmagno, Jenniskens, Kolomiets, Koten, Marsden, Porubčan, Spurný, Valsecchi, Watanabe, and Williams. [ABSTRACT FROM PUBLISHER]

The IAU Meteor Shower Working List contains 369 showers, of which only 64 are considered established (per February 28, 2012). In this invited review, we will give an overview of international efforts to validate the remaining showers. We report on the showers that were validated in this triennium and proposed to receive the predicate “established" at the present General Assembly. The meteoroid orbit surveys characterize the meteoroid streams in terms of orbital elements and their dispersions, which is ground truth for efforts to identify their parent comets, study the fragmentation history of the (mostly dormant) comet population in the inner solar system, and understand the origin of the zodiacal cloud. [ABSTRACT FROM PUBLISHER]