mapping-KEY-edit
pdf
keyboard_arrow_up
School
Bakersfield College *
*We aren’t endorsed by this school
Course
MISC
Subject
Astronomy
Date
Dec 6, 2023
Type
Pages
4
Uploaded by jessicaperez212102
3.1.
MAPPING THE SOLAR SYSTEM FROM EARTH – KEY
47
3.1
Mapping the Solar System from Earth – KEY
Courtesy of Adams and Slater and CAPER Team
Part I: Rising and Setting Times
to Sun
Noon
Figure 1-a: Observer positions
on Earth. (Observer is at Equator)
As seen from above, Earth appears to rotate
counterclockwise. Figure 1-a shows a top view
of Earth and an observer at noon. Note that our
Sun appears overhead when standing at the
equator.
This is a
crucial
diagram that you will
refer to in the rest of this assignment!
1. In
Figure 1-a
, sketch and label the positions of
the observer and his horizon at midnight,
6 PM (sunset) and 6 AM (sunrise).
The top of each observer’s head is pointed
to the meridian direction in space. For
example, at 6 PM the observer’s meridian
is oriented directly to the left of this figure.
Note that the horizon spins (rotates) with
the observer!
2. Consider
Figure 1-b
, which shows Earth,
Moon, Mars, Mercury, and Venus. At what
time would each of these sky objects be
highest (on the meridian)? Remember
that Earth spins counterclockwise when
viewed from above. [
Hint: Make use of
Figure 1-a
]
Time Overhead:
Venus:
Moon:
Mars:
Mercury:
Sun
Figure 1-b: Orrery
6 PM sunset
Midnight
6 AM sunrise
Noon
6 AM sunrise
Venus
Mercury
Mars
Noon.
Venus is in same direction
as Sun. I drew the noon observer from
Figure 1a onto Figure 1b.
Midnight.
At midnight observer
is facing down toward bottom of
Figure 1-b.
6 AM (sunrise).
I drew the 6 AM
observer from Figure 1a onto Fig 1b.
arrow is
meridian
between 6 AM
and noon.
Mid-morning.
Mercury is between
Mars and Sun on sky, so meridian
time is between that for Mars and Sun.
East
West
East
West
East
West
East
West
48
Mapping the Solar System from Earth
3. If Earth spins 360
◦
in 24 hours, that means that each sky object is visible for about 12 hours.
What time will the sky objects shown in Figure 1-b rise and set? Complete the table below
(and refer back to Figure 1-a!).
Each member of your team should fill in the data for one sky
object.
12 AM is midnight, and 12 PM is noon, but use “noon” or “midnight” instead of 12
PM and 12 AM. (Recall that an object is at its highest altitude when it is on the
meridian
.)
Sky Object
Rise Time
Time on Meridian
Set Time
Sun
6 AM
Noon
6 PM
Venus
6 AM
Noon
6 PM
Moon
6 PM
Midnight
6 AM
Mars
Midnight
6 AM
Noon
4. Using complete sentences, explain why our Sun is not visible at midnight. Add a sketch of
Earth, Sun, and observer in the space provided to support your explanation.
Narrative
At midnight we are facing directly away from
the Sun (our meridian is oriented opposite the
Sun toward the outer part of the solar system).
At midnight the Earth blocks our view of
things roughtly in the same direction as the Sun
and we can only see things that arepositioned
toward the outer part of the solar system.
Sketch
HORIZON
above horizon (things visible)
below horizon (things blocked
by Earth)
Sun
Part II: Converting Geocentric to Heliocentric
5.
Figure 2-a
on the next page shows the horizon view of the first quarter Moon and Saturn
visible at sunset. On the orrery shown in Figure 2-b, you will sketch and label the position
of Jupiter, Moon, and Saturn.
(1) First use an arrow to indicate the direction to the Sun
in Figure 2-b. (2) After drawing the arrow, indicate the position of the observer at
sunset.
(
Recall
figure 1-a: at NOON, the observer is facing directly toward the Sun and the Earth
spins counter-clockwise.)
(3) Draw the observer’s horizon at sunset.
(4) Sketch and label
the position of Jupiter, Moon, and Saturn. (
Recall
the observer is pointed directly toward
an object if the object is on the observer’s meridian—due South.) (5) After completing the
diagram, complete the table.
12 AM is midnight, and 12 PM is noon, but use “noon” or
“midnight” instead of 12 PM and 12 AM.
Mapping the Solar System from Earth
49
South
East
West
x
zenith
Figure 2-a:
Horizon View at sunset (6 PM)
Saturn (rising)
Moon
to Sun
at sunset
Jupiter
Earth
Saturn orbit
Jupiter orbit
Figure 2-b:
Orrery NOT drawn to scale!
Sky
Object
Sun
Jupiter
Moon
Saturn
Rise
Time
Set
Time
6 AM
6 PM
Noon
Midnight
Noon
Midnight
little before
6 PM
little before
6 AM
to Sun (and
noon meridian)
remember Earth
spins counter-clockwise
6 PM sunset
meridian direction
HORIZON
Person facing south
sees Saturn on his
left. Horizon line
spins in counter-
clockwise direction.
Moon
Jupiter
Saturn
I also drew in the
observer and his
horizon line.
Meridian goes
through exact
south and
zenith.
dotted line
is meridian
arc
Jupiter and Moon are on
the meridian (or very
close => observer’s part
of Earth is pointed right
toward the Moon and Jupiter.
6. If Neptune is visible on the meridian in the southern sky at sunrise (6 AM), sketch the relative
positions of Sun, Earth, Neptune, and observer with his horizon in an orrery in the space
below. (
Recall
figure 1-a: at NOON, the observer is facing directly toward the Sun and the
Earth and horizon spins counter-clockwise—so what direction are we facing at 6 AM? Also
the observer’s part of Earth points toward whatever object is on the meridian.)
To Sun
Earth
6 AM sunrise
Neptune
meridian of
6 AM person
If Sun is at the bottom of the figure,
then rotate Figure 1-a 180º so person
is facing toward the left side at sun
rise.
Direction person is facing is the direction
of the meridian, so Neptune should be
in that direction (i.e., to the left side
of the picture).
HORIZON
Horizon rotates
counter-clockwise
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
50
Mapping the Solar System from Earth
Part III: Converting Heliocentric to Geocentric
Figure 3-a: Orrery
comet orbit
7.
Figure 3-a
shows the position of
Mercury, Venus, Earth, Mars, Moon
and a comet in an orrery diagram.
On the horizon diagram,
Figure 3-b
,
sketch and label the
positions of
Mercury, Venus, Mars, Moon and
the comet at
midnight
. (In Figure 3-a
which direction is the observer facing
at
midnight
?)
Figure 3-b: Geocentric Horizon View at Midnight
South
East
West
x
zenith
In Figure 3-a, the observer
is facing to the right side
of the figure (I drew her in).
Her meridian is oriented to
the right side of the figure so
East is on
her
left toward the comet.
Horizon line rotates counter-clockwise!
HORIZON
comet (rising)
First quarter
Moon (setting)
Mars
Mercury and Venus
are
below
the horizon
(not visible)
East
West
comet
Mercury
Venus
Moon
Mars
Draw the positions of the objects in the sky as we would see them from on the ground,
i.e., translate Figure 3-a to Figure 3-b. If an object is below the ground at midnight, be sure
to explicitly say so or draw it and label it below the ground.
Need to note that Mercury and Venus are below the horizon because question includes them
in the instructions!
8. Venus is often called the
morning star
or
evening star.
Why is it never seen at midnight?
Why is it always the case that it is below the horizon at midnight?
At midnight we (our part of the Earth) are pointing directly away from the Sun and we can
only see things that are farther out from the Sun than we are. Venus’ orbit is smaller than
ours and never carries Venus to beyond the Earth’s orbit.
Venus always appears near the
Sun because its orbit is inside our orbit. The orbit size is the CAUSE. To say that Venus is
below the horizon or it has already set begs the question of why that is ALWAYS the case at
midnight.