> 
> The Cambridge Philosophical Society is holding the third lecture of the Lent 
> Term at the Bristol-Myers Squibb Lecture Theatre, in the Department of 
> Chemistry on Monday 12 February 2018 at 6.00 pm. The Speaker is Professor 
> Richard Harrison, Professor of Earth and Planetary Materials, Department of 
> Earth Sciences, whose lecture is entitled "Magnetic microscopy of meteorites: 
> probing the magnetic state of the early solar system".
> 
> Abstract as follows:  Microstructural and geochemical studies of meteoritic 
> metal have been instrumental in shaping our current views of differentiated 
> asteroids, providing constraints on their cooling rate, their size, the 
> timing of their differentiation and their fractional crystallisation and 
> impact histories. The characteristic Widmanstätten microstructure, familiar 
> to anyone who has looked at a polished and etched section of an iron 
> meteorite with the naked eye, hides a nanoscale complexity that is revealed 
> only with high-resolution electron microscopy – a legacy of stranded 
> diffusion profiles, metastability, martensitic transformations, chemical 
> segregation and ordering during slow cooling over millions of years on the 
> parent body. The presence of soft bcc iron has traditionally lead to the 
> meteoritic metal being dismissed as a reliable carrier of paleomagnetic 
> information. However, we have shown that, under favourable circumstances, 
> paleomagnetic information can be recorded and retained on a local scale 
> within a unique nanoscale intergrowth called the cloudy zone (CZ). 
> High-resolution X-ray imaging methods enable the magnetic state of the CZ to 
> be imaged and analysed quantitatively, opening up new avenues of research 
> into the nanopaleomagnetism of a range of meteorites. Such studies are not 
> only revealing new insight into the thermochemical properties of asteroids in 
> the early solar system, but provide us with unique opportunities to learn 
> about how magnetic fields are generated on planetary bodies in general, and 
> the underlying physics of the dynamo generation process itself.
> 
> The lecture is free (no booking required) and open to all who are interested 
> and will be an excellent opportunity to hear an eminent scientist.
> 
> Entrance to the Bristol-Myers Squibb Lecture Theatre, is adjacent to the 
> Scott Polar Research Institute on Lensfield Road
> 
> If you wish to be removed from this mailing,  please email 
> philo...@hermes.cam.ac.uk <mailto:philo...@hermes.cam.ac.uk> quoting the 
> reference at the end of the subject line to this email.
> --
> Mrs Beverley Larner
> Executive Secretary
> Cambridge Philosophical Society
> 17 Mill Lane
> Cambridge CB2 1RZ
> 
> Tel: 01223 334743
> Email: philo...@hermes.cam.ac.uk <mailto:philo...@hermes.cam.ac.uk>
> Website:  www.cambridgephilosophicalsociety.org 
> <http://www.cambridgephilosophicalsociety.org/>
> 
> 
> 
> 
> 
> 
> 
> 
> 

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