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More Potential Hazardous Asteroids than what we thought – the Chelyabinsk event

Zuluaga J.I., Ferrína, I, and Geens, S., 2013, arXiv:1303.1796
The orbit of the Chelyabinsk event impactor as reconstructed from amateur and public footage

The Chelyabinsk meteor is the most important impact event after the Tunguska event, almost 100 years before. The object that entered Earth on February 15, 2013, was a small-sized Apollo asteroid (with a diameter of 17-20m), and caused serious damages. This fact proves according to the authors that the number of Potential Hazardous Asteroids (PHA) are almost double that what is thought, although most of them (with diameters smaller than 100m) are not capable of global damage but can cause severe local damages. They state also the fact that the approaching direction was from the Sun side, which is a totally blind spot currently at the existing optical surveys.

Geminids and their mysterious parent body 3200 Phaethon

The Geminids are one of the best meteor showers of the year with numerous (ZHR~120) and bright (r~2) meteors! The parent body is an asteroid named 3200 Phaethon, which is believed to be a candidate for an extinct cometary nucleus, a mystery by itself. Moreover, during the last perihelion passage of the asteroid its magnitude increased unexpectedly (almost doubled), which is thought to be connected to some ejected dust originated from break-down of surface rocks. But this dust can account only for the 0.01% of the total material which is needed to supply the stream in order to see this activity each year this show.

How this object has manage to give out so much material? Geminids are not ready yet to reveal their mysteries…

The source and paper ( by journal or author) / Jewitt D. & Li J., Activity in Geminid parent (3200) Phaethon, AJ, 140, 1519, 2010.