The 'Sir' is from being 'knighted' by the queen (or king) of England.
"Isaac Newton was Sit Isaac Newton's real name.
Isaac Newton
His name was also Isaac Newton
His full name was Sir Isaac Newton. Isaac is his first name.
Newton was knighted in 1705
Sir Isaac newton.
Sir Isaac Newton
Born Isaac Newton, later to become Sir Isaac Newton.
His birth name was Isaac Newton; he had no other names.He was knighted in 1705 and thereafter his whole name was "Sir Isaac Newton"
Hannah Newton
jessica newton
Isaac's father was also named Isaac newton.