TWINKLE, TWINKLE, LITTLE STAR

BrainPOP: Life Cycle of Stars

What are stars?

Giant balls of gas that undergo nuclear fusion.

Nuclear fusion is when the nuclei

of two atoms join together to make

a bigger nucleus and release energy.

1. Composition (what it is made of)

2. Size3. Color (temperature)4. Brightness

Composition

73%

25%

2%

Hy-dro-genHeliumOther

Stars are made up of mostly two gases, which ones are they?

Find it on

pg.93!

Size

Supergiantor

Giant

Main Sequenc

eDwarf

The color of a star indicates

its temperature.

The SunOur Sun is a main sequence, yellow star.

Sun Song

Its not the biggest OR the hottest in the universe!

Brightness

The brightness of a star depends on both the size and temperature of the star.

But, how bright it APPEARS to us depends on how far it is from Earth and how bright it truly is.

We can measure a star’s brightness in two ways:

How bright a star actually is.

(depends on

How bright a star appears from Earth.(depends on star’s

distance from Earth)

Apparent Magnitude Absolute Magnitude

Stars can appear brighter or dimmer depending on their distance from Earth.

Which headlights are brighter? Why?

In Class Example

Exit Slip: Stars1. What 5 characteristics are used to classify stars? 2. What can the color of a star tell you about it?

3. Which color star is hottest?

4. What size and color is our Sun?

5. Stars are made of mostly which two gases?

Hertzsprung-Russell Diagram

Over 90% of all stars (including our

Sun) are main sequence stars.

OMG, when is the sun going to die?!?

The Sun’s estimated life is 10 billion years…

AND….

The sun is halfway through its life!

Characteristics of Stars Worksheet

Answer # 1-5