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<TITLE>CORRECTION: Two Malhotra talks this week</TITLE>
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<P ALIGN=CENTER><FONT FACE="Times New Roman">CfA Institute for Theory and Computation Colloquia</FONT></P>
<P ALIGN=CENTER><B><FONT FACE="Times New Roman">TUESDAY, SEPTEMBER 13</FONT></B></P>
<P ALIGN=CENTER><B><FONT FACE="Times New Roman">12:30 pm, Pratt Conference Room</FONT></B></P>
<P ALIGN=CENTER><B><FONT FACE="Times New Roman">"Eccentric Extra-Solar Planets"</FONT></B></P>
<P ALIGN=CENTER><B><FONT FACE="Times New Roman">Prof. Renu Malhotra</FONT></B></P>
<P ALIGN=CENTER><FONT FACE="Times New Roman">University of Arizona. </FONT></P>
<P><B><I><FONT FACE="Times New Roman">Abstract</FONT></I></B><I></I><FONT FACE="Times New Roman">: Orbital eccentricities in exo-planetary systems discovered thus far are often surprisingly large and pose a challenge to planet formation theory. In multiple-planet systems, there is also a tendency for alignment of the major axes of two planets. The best-constrained case is that of Upsilon Andromedae: new data indicates a history of strong dynamical perturbation in this system, and suggests that the phenomenon of planet-planet scattering may be a natural explanation for eccentric planets. </FONT></P>
<P ALIGN=CENTER><FONT FACE="Times New Roman">Astronomy Colloquia</FONT></P>
<P ALIGN=CENTER><B><FONT FACE="Times New Roman">THURSDAY, SEPTEMBER 15</FONT></B></P>
<P ALIGN=CENTER><B><FONT FACE="Times New Roman">4:00 pm, Phillips Auditorium</FONT></B></P>
<P ALIGN=CENTER><B><FONT FACE="Times New Roman">"The Origin of Planetary Impactors in the Inner Solar system"</FONT></B></P>
<P ALIGN=CENTER><B><FONT FACE="Times New Roman">Prof. Renu Malhotra</FONT></B></P>
<P ALIGN=CENTER><FONT FACE="Times New Roman">University of Arizona. </FONT></P>
<P><B><I><FONT FACE="Times New Roman">Abstract</FONT></I></B><I></I><FONT FACE="Times New Roman">: The Moon and all the terrestrial planets were resurfaced during a period of intense impact cratering that occurred between the time of their accretion, ~4.5 billion years ago, and ~3.85 billion years ago: the crater record and radiometric dating of lunar rocks attests to this conclusion. However, identifying the source(s) of those planetary impactors has proven elusive; speculations have included comets, asteroids, and fragments of a shattered 'large planetesimal'. I will describe compelling new evidence that the source of the impactors was the main asteroid belt, and that the dynamical mechanism that caused the so-called 'Late Heavy Bombardment' ~3.9 billion years ago was unique in the history of the Solar System and distinct from the processes producing the flux of objects that currently hit planetary surfaces. The Late Heavy Bombardment was a rain of asteroids dynamically ejected from the main asteroid belt due to the effects of orbital migration of Jupiter and Saturn. </FONT></P>
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