GIORDANO-BRUNO, THE JUNE 1975 METEOROID STORM, ENCKE, AND OTHER TAURID COMPLEX OBJECTS

The Tunguska event on the Earth and a seismically detected meteoroid "storm" on the Moon occurred in late June, and the objects producing these events arrived at the Earth or Moon from the same direction, thus suggesting a common source. The arrival direction of the object that produced the lunar crater Giordano Bruno is poorly constrained, but a similar arrival direction and a common source for this object cannot be ruled out. Laser ranging of the Moon may confirm or refute the predicted direction of momentum transfer during the impact. Other Solar System objects which cross the Earth's orbit at the same time of the year and arrive from the same direction are the meteoroids of the beta-Taurid meteor stream, the comet, Encke, long considered to be related to Taurid meteors based on the similarity of their orbits, and the asteroids 2201 Oljata and DS 1978. Secondary or ejecta fragments from impacts of primary Taurid Complex objects have been detected. One group of these secondaries was probably detected by the HEOS-2 dust detector in June of 1973. Corvid meteors observed only in late June of 1937 may be secondaries from the Giordano Bruno impact in June of 1178. Objects that products meteorite falls, fireballs, airwaves, and flashes on the Moon do not show a preference for late June and, therefore, are not part of the Taurid Complex. Objects that make up the Taurid Complex are survivors of a long history of impacts and collisions that continuously reduce large objects to small ones. The apparent inconsistency of long lifetimes against collision or perturbation for Encke-like orbits together with short lifetimes against mass loss by evaporization and ejection of solid particles from Encke-like objects may be reconciled if the early ancestors of today's Taurid Complex have existed in the inner Solar System, inactive and undetected, since their constituents were condensed and accreted from the presolar nebula. © 1993 Academic Press. All rights reserved.