STARSChapter 8 Section 1

What we will talk about today

• What color tells us about the temperature of a star

• How we can identify what a star is made of

• How a star’s brightness, location, and distance from earth are measured

What are stars?

• Stars are huge, bright balls of burning gas.• Stars are different colors because of their

temperatures, and scientists can tell how much heat a star gives off by studying its color.

• Who has used atelescope?

Bunsen Burner vs. Candle

What flame is hotter? The flame of the Bunsen burner or the candle?

Colors of Stars

• A blue flame is much hotter than a yellow one.• Stars are similar: blue stars burn hotter than

yellow ones.• Red stars are coolest. • This is Betelguese, a Red Giant Star What color is our sun?

What temperatures are these stars?

What are stars made of?

• Stars are made of gas. Hydrogen(H) and helium(He) are the two main elements that make up a star.

• What is an element? • Stars also contain small amounts of other elements,

such as carbon, nitrogen, and oxygen. Each star is made up of a different mix.

• To find out what a star is made of scientists study the light from the stars.

What is light?

Light is actually made up of many colors. These colors are called the spectrum.

• Many colors make up a spectrum, including **red, orange, yellow, green, blue, indigo, and violet. ROY G BIV will help you remember the

spectrum. Where else have you seen these colors?

Why do Scientists Study Light?• Scientists are able look at light through a machine

called a spectrograph to break up a star’s light into a spectrum.

• Each element has a particular pattern of lines that appear in an emission spectrum. The emission spectrum shows scientists what elements are in the star.

• What can studying a star’s spectrum tell an astronomer?

Another way to describe stars: Magnitude or Brightness

• Scientists give each star a number to show its brightness, or magnitude.

• The dimmest stars have the largest magnitude numbers.

• The brightest stars have the smallest magnitude numbers.

What is the brightest star?

Quick Vocabulary Review

• What does apparent mean?1)Clearly understood 2)Seeming real or true, but

not necessarily so.• What does absolute mean? complete• What does actual mean? Existing in fact

One type of magnitude

• The brightness(or magnitude) of a star as we see it from Earth is the star’s apparent magnitude.*** A bright star can look very dim if it is very far away from Earth. A dim star can appear bright if it is closer to Earth.

• Where would you see the apparent magnitude of a star?

Absolute Magnitude

• A star’s absolute magnitude is the actual brightness of the star.

• Astronomers use a star’s apparent magnitude and its distance from earth to calculate its absolute magnitude.****

• What can we tell aboutthese stars magnitudes?

What do scientists use to calculate distance to stars?

• Because stars are so far away, astronomers use light years to measure the distance from Earth to the stars.

• A light year is the distance that light travels in one year, or 186,282 miles per second, or 5.88 trillion miles****

This quasar is 10 billion light years from Earth

Motion of the Stars

Measuring the distances of starswith parallax****

• Parallax is the object’s apparent shift in motion when viewed from different locations. It is an optical effect.

• Astronomers can measure parallax and use it to calculate exact distances to stars.

• Does the man on the right(V2) see the moon as closer or farther away than the man on the left?

• Where would someone use parallax?

To sum it all up…….

Why do some stars look different than others?

When we look at a star from Earth, will it look the same in 6 months? Why?