Nila

Hi there! While charging a metal sphere(connected to earth) negatively by induction,by bringing a positively charged rod near it,why does the electrons flow from earth to the sphere? When we want to charge the sphere positively by induction,the electrons flow out from the sphere when connected to earth. Why does it happen? Could someone care to enlighten me on this? Thank you in advance! Good Day BTW,I'm new here! Nice to meet you all. Nila