Distant supernovae appear fainter than we expect them to for a flat universe. as a result astronomers think we live in a universe that

is expanding

Explanation:

A supernova is a stellar explosion that occurs as a result of the final stage of a star's life. This event can be very remarkable, even observable to the naked eye. This means that supernovae are characterized by very intense flashes of light that can last from several weeks to several months. In addition, its luminous intensity increases rapidly until it reaches an absolute magnitude greater than the rest of the galaxy, and then gradually loses its brightness until it disappears completely.

Then, a supernova is a very bright element, however, as its distance from the observer is greater, they will be less luminous (look fainter). This is presented as proof that we live in a universe that is expanding and is not flat.

wow this is so hard for me im only in elementry school still!

i think the answer to your question is: settlement of the interior and economic growth. ( ^_^)／