What is the name of the imaginary line dividing Earth into northern and southern hemispheres?

The Equator

What is the name of the massive black dog belonging to Rubeus Hagrid in the "Harry Potter" series? What type of animal is a gecko? Which aromatic herb has tiny elongated leaves frequently used as seasoning in Southern European cooking? Who performed the hit single "All Star"? What's the sum of exterior angles of any polygon regardless of its number of sides?