Download What is a Scientist? - Cockeysville Middle School

Objective: To distinguish between absolute and
apparent magnitude in order to
describe the brightness of stars.
Astronomy Note: How bright are stars?
Drill:
1. Take out your ditto, “Vocabulary of the
Universe”.
2. Get a new ditto from the SET.
3. Complete Activity 1, # 1-2.
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STAR: a giant sphere of glowing gases
What questions might someone have about
the definition?
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STARS
Stars are giant spheres of glowing gases. A star is powered
by nuclear fusion. This is a process whereby hydrogen
atoms are fused together to create helium atoms. In the
process a tremendous amount of energy is given off in the
form of electromagnetic waves and heat. There are billions
of stars in a galaxy. When you look up into the night sky,
most of the stars appear to be about the same size.
However, in reality the sizes of different stars vary greatly.
The closest star to earth is our sun. It is about 150 million
km away. This distance is referred to a 1 Astronomical Unit
(AU). The next closest star to Earth is Proxima Centauri. It
is about 250,000 AU from Earth.
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What are 2 things you learned
from the passage?
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Activity 2: Brightness (Magnitude) of
Stars
Description of the
Position of the Flashlight
Observation of the
Brightness of the Light
1 meters from the screen
fairly bright
6 meters from the screen
Very dim
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Why do you think there was a difference in
the brightness of the two flashlights? Use
prior knowledge to support your response.
Different Distances
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Did the two flashlights actually differ in
their brightness? Explain.
Same Brightness: One appeared brighter
because it was closer to the screen.
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Read Page 129 in order to distinguish
between absolute and apparent brightness.
Flip your tag to green when you think you
understand.
Can you come up with your own examples
to explain how they are different?
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Apparent and Absolute Brightness
Apparent Brightness: the brightness of a star
or object as seen from a particular location.
This can be thought of how bright something
appears, and is affected by distance.
Absolute Brightness: the brightness of a star or
object as seen from a standard distance from a
particular location. This is the true brightness.
It is not affected by distance.
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DISCUSSION
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Is our sun the brightest object in
our sky? Explain your answer.
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