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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