Does the word hemisphere have to be capitalized in a sentence?

No, the word "hemisphere" does not need to be capitalized in a sentence unless it is the first word of the sentence or part of a proper noun.

Here are some examples:

Not Capitalized:

* The Earth is divided into two hemispheres: the Northern and Southern Hemispheres.

* The Western Hemisphere includes North and South America.

* The brain is divided into two hemispheres: the left and right hemispheres.

Capitalized:

* Hemisphere is a term used to describe half of a sphere.

* The Western Hemisphere is home to a diverse range of cultures.

* The Southern Hemisphere experiences winter during the months of June, July, and August.

Remember:

* Proper nouns are specific names of people, places, or things and are always capitalized.

* Common nouns are general names for people, places, or things and are not capitalized unless they are the first word of a sentence.