What do you think?


Do the stars stay in the same position in the
sky all day/night long?
Do we see the same stars all year round
every night?
What do you think?



What causes the stars to move?
Do the stars actually move in the way they
appear to be moving from Earth?
Is the daily motion of the Sun different from
the stars?
Consider the dome of the sky over our heads….
mixing bowl
Consider the dome of the sky over our heads….
inverted mixing bowl ….
Imagining a
spinning
Celestial
Sphere
surrounding
Earth aids in
thinking about
the position
and motion of
the sky.
Imagining a
spinning
Celestial
Sphere
surrounding
Earth aids in
thinking about
the position
and motion of
the sky.
Imagining a spinning Celestial
Sphere surrounding Earth aids in
thinking about the position and
motion of the sky.
What would this
look like from the
ground?
Celestial Sphere Rotation
Celestial Sphere Rotation
Star B
Star B
2
2
Star A
Star A
1
2
1
2
North Star
Celestial Sphere
Celestial Sphere
3
3
1
1
4
4
3
3
Earth’s Equator
4
4
Celestial Sphere
Rotation
Celestial Sphere
Rotation
Figure 1
Figure 2
Horizon
Pre Tutorial Question

You observe a star rising due east. When this
star reaches its highest position above the
horizon, where will it be?
A) high in the northern sky
B) high in the eastern sky
C) high in the southern sky
D) high in the western sky
E) directly overhead
Tutorial: Position – p.1

Work with a partner.

Read the instructions and questions carefully.




Talk to each other and discuss your answers with
each another, but BOTH write in your own book.
Come to a consensus answer you both agree on.
If you get stuck or are not sure of your answer, ask
another group.
If you get really stuck or don’t understand what the
Lecture Tutorial is asking, ask me for help.
Is the horizon shown a real physical
horizon, or an imaginary plane that
extends from the observer and
Earth out to the stars?
Celestial Sphere Rotation
Star B
2
Can the observer shown see an
object located below the horizon?
Star A
1
2
Celestial Sphere
Is there a star that is in an
unobservable position?
When a star travels from being
below the observer’s horizon to
being above the observer’s horizon,
is that star rising or setting?
Celestial Sphere
3
1
4
3
4
Celestial Sphere
Rotation
Figure 2
Horizon
Post Tutorial Question

Stars that never appear to set are called
circumpolar. As you move from Earth’s equator
toward the North Pole, the number of stars that
are circumpolar
A) increases.
B) decreases.
C) stays the same.
Post Tutorial Question

Imagine you are standing at the North Pole. Of
the stars that you can see, roughly how many of
these stars are circumpolar?
A) none
B) less than half
C) more than half
D) all
Post Tutorial Question

You are observing the sky from your southern
hemisphere location in Australia. You see a star
rising directly to the east. When this star
reaches its highest position above the horizon,
where will it be?
A) high in the northern sky
B) high in the eastern sky
C) high in the southern sky
D) high in the western sky
E) directly overhead

In what direction would
you face (look) to see
Star A when it is
highest in the sky?
A) toward the north
B) toward the south
C) toward the east
D) toward the west
E) directly overhead

Which of the stars will
set on the western
horizon?
A) both Star A and Star B
B) only Star A
C) neither Star A nor Star B
D) only Star B