If you cut a ball in half, each half is a hemisphere. Mapmakers cut Earth in half in two ways.
Key idea
The equator cuts Earth into the Northern and Southern Hemispheres. A line from pole to pole cuts it into the Eastern and Western Hemispheres.
Why it works
The east-west cut follows the line from the North Pole to the South Pole through London, England, and the line on the other side of the world. Since there are two different cuts, every place is in two hemispheres at once: one northern or southern, and one eastern or western.
Worked example: Two at once
The United States is north of the equator and west of London's line. Which hemispheres is it in?
- North of the equator: the Northern Hemisphere.
- West of London's line: the Western Hemisphere.
Answer: The Northern and Western Hemispheres. (A few of Alaska's far-off islands cross into the east.)
Common mistake
Children think a place can be in only one hemisphere. Every place is in two: north or south, and east or west. Australia is in the Southern and Eastern Hemispheres.
For the grown-up. Cut an orange in half across the middle (north and south), and another one from top to bottom (east and west). Talk about which half your home is in.