Replying to Know History?

if you know any history you can help me out.

you can help me greatly by telling me the significance of each of the following

-Ferdinand Magellan Circumnavigating the globe

-Christopher Columbus 'discovering' America

-Alexander the great traveling into Asia

-Leif Erikson Discovering North America

-Lewis and Clarks Pioneering the west

-James Cook Sailing around Australia


What was the significant impact the journey had on mankind?

thanks