Who is Leon Foucault?

this will help you know who he is.

who was he and where did he live and how old would he be today

He would be 194 years old and he lived in France and taught us that the Earth spins and is not flat.http://en.wikipedia.org/wiki/L%C3%A9on_Foucault

What did he study and how does the Foucault Pendulum work?

After he got his education from home he studied medication.The foucault pendulum work by showing the rotates once every 24 hours.http://www.si.edu/Encyclopedia_SI/nmah/pendulum.htm

why was his research and invention so significant in the field of Earth science?

Foucault demonstrated that it’s actually the Earth underneath that is moving. The pendulum precesses at varying rates north or south of the equator, making the experience of seeing it unique at each latitude.

thats all and i hope this has helped you.