Chapter 21 Test: Stars, Galaxies, and the Universe

Front

What type of magnitude do astronomers use to compare the brightness of stars?

Back

Absolute magnitude.

Front

True or False: Astronomers measure the distance of a star in units called kilometers.

Back

False. Astronomers use light years.

Front

What determines the length of a star’s life?

Back

The mass of the star.

Front

True or False: Scientists use light years to measure objects in space because of the vast distances involved.

Back

True.

Front

What process allows a protostar to become a star?

Back

Nuclear fusion.

Front

What is the definition of a light year?

Back

A light year is the distance that light travels in one year, approximately 5.88 trillion miles.

Front

What is the difference between absolute and apparent magnitude?

Back

Absolute magnitude measures a star's intrinsic brightness, while apparent magnitude measures how bright a star appears from Earth.

Front

What is a protostar?

Back

A protostar is a young star that is still in the process of forming, before nuclear fusion begins.

Front

What role does mass play in a star's lifecycle?

Back

A star's mass determines its temperature, luminosity, and lifespan.

Front

What is nuclear fusion?

Back

Nuclear fusion is the process by which two light atomic nuclei combine to form a heavier nucleus, releasing energy.