Question

stars
before you read
after you read this section, you should be able to answer these questions:

• why are stars different colors?
• how can scientists learn what stars are made of?
• how can we measure the distance between stars?
• why do stars seem to move across the sky?

why are stars different colors?
stars look like tiny points of light in the sky. however, they are actually huge, bright balls of burning gas. if you look closely at the night sky, you might see that stars are different colors. scientists can tell how much heat a star gives off by studying its color.
compare the yellow flame of a candle to the blue flame of a bunsen burner. a blue flame is much hotter. stars are similar: blue stars burn hotter than yellow ones. red stars are coolest.
a blue flame is hotter than a yellow one.
what are stars made of?
stars are made of gas. hydrogen and helium are the two main elements that make up a star. stars also contain small amounts of other elements, such as carbon, nitrogen, and oxygen. each star is made up of a different mix of elements.
most stars are trillions of miles away from earth. because scientists cannot visit the stars, they need to study stars from earth. to find out what a star is made of, scientists study the light from the stars.
study tip
ask questions read this section quietly to yourself. write down questions that you have about this section. discuss your questions in a small group.
take a look

1. color use colored pencils to make these flames the correct color.
2. identify which of the flames is cooler?

reading check

1. explain how do scientists learn about stars?

Explanation:

1. Stars have different colors because their surface - temperatures vary. Hotter stars are bluer, cooler ones are redder.
2. Scientists learn what stars are made of by studying the light they emit, as different elements produce unique spectral lines in starlight.
3. Measuring the distance between stars can be done using methods like parallax (for nearby stars) and standard candles (for more distant ones).
4. Stars seem to move across the sky due to Earth's rotation on its axis and its orbit around the Sun, as well as the proper motion of the stars themselves.

For the "TAKE A LOOK" and "READING CHECK" questions:

1. Color the blue flame with a blue - colored pencil and the yellow flame with a yellow - colored pencil.
2. The yellow flame is cooler.
3. Scientists learn about stars by studying the light from the stars. The light contains information about the star's temperature, composition, and other properties.

Answer:

1. Color the blue flame blue and the yellow flame yellow.
2. The yellow flame is cooler.
3. Scientists learn about stars by studying the light from the stars.