£££ Jack Oughton - Planetary Science Presentation 03 - A Brief Guide To Terrestrial Magnetism and Field Reversals.ppt

A Brief Guide To Magnetism, Terrestrial Magnetic Field and Polar Reversals Jack Oughton 

Definitions Dynamo - A system that uses electromagnetic induction to convert mechanical energy (motion) into a magnetic field Ferromagnetism is believed to be caused by magnetic fields generated by the electrons' spins in combination with a mechanism known as exchange coupling , which aligns all the spins in each magnetic domain. Curie temperature (Tc ) The temperature above which a ferromagnetic material loses its permanent magnetism. In minerals, lightning often flash-heats minerals above their Curie temperatures, effectively resetting the magnetic fields trapped in lava flows.

All known magnetic fields are caused by the movement of electrical charges . Electrons in orbit in atoms give rise to magnetic fields, so that every atom is, like the Earth, surrounded by a magnetic field Magnetism in a nutshell ,[object Object],[object Object],[object Object],[object Object],A magnet cannot have a single North pole or a single South pole, which would be called a ‘monopole’

Importance of the poles ,[object Object],[object Object]

The Magnetic Field ,[object Object],[object Object],[object Object]

Our Magnetic Field / The Magnetosphere ,[object Object],[object Object],[object Object],[object Object]

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Cause of the Field – The Dynamo effect ,[object Object],[object Object],[object Object],[object Object]

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what does the magnetic field do ? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Magnetic Polar Wandering ,[object Object],[object Object],[object Object],[object Object]

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How do we tell there have been shifts in the past? ,[object Object],[object Object],[object Object],[object Object],[object Object]

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Paleoreversal / ‘flips’ ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

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Measuring The Field’s Changes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The Reversal In Fiction ,[object Object],[object Object]

The Orion Prophecy – an example ,[object Object],[object Object],[object Object],[object Object]

Summary – Realistic Outlook? ,[object Object],[object Object],[object Object],[object Object],[object Object]

References ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

£££ Jack Oughton - Planetary Science Presentation 03 - A Brief Guide To Terrestrial Magnetism and Field Reversals.ppt

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