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Second Astronomy Practice Exam:
1. The ancient Ptolemaic astronomers had deduced an order for the
planets as one proceeded away from the Earth towards the stellar
sphere. See figure to the right. On which of the following
apparent properties of the planets was this order based upon?
a. Apparent Magnitudes of the Planets (i.e. their brightness)
b. Maximum elongation angles
c. Periods of retrograde motion
d. Time to cycle the zodiac
e. Their mythological hierarchy
2. On the diagram to the right label the deferent, epicycle and equant.
3. Where is a planet on its epicycle when it goes retrograde? Why does it
go retrograde only when it is on that part of its epicycle? Answer in a
sentence or two.
4. Why was an equant, or similar device, necessary in the Ptolemaic model? Illustrate with an example.
Answer in a few sentences.
5. In 1543 Copernicus proposed that the Earth was a planet. What motions did Copernicus attribute to the
Earth? Be complete in your answer. Answer in a few sentences.
6. In a sentence or two explain how the modern Copernican model of the Universe explains why inferior
planets have a maximum elongation.
7. In a sentence or two explain how the modern Copernican model of the Universe explains the occurrence
of retrograde motion coincident with opposition and brightening for the superior planets.
8. The figure to the right illustrates Copernicus’ original
heliocentric model of the Solar System. As you can see it is
quite complex compared to the simpler model we use today.
What two flaws in the original Copernican model created this
complexity? Answer in a sentence.
9. Kepler’s first two Laws of Planetary Motion contradicted the Aristotelian/Ptolemaic Model of the
Universe in two fundamental ways. State Kepler’s first two Laws of Planetary Motion and how were
they anti-Aristotelian? Use appropriate vocabulary. Answer in a few sentences.
The figure below is an ellipse. The axes are marked in units of AUs. The position of the Sun is marked.
Answer the questions that appear below the figure by filling in the blanks.
10
8
6
4
2

0
-10
-8
-6
-4
-2
0
2
4
6
8
10
-2
-4
-6
-8
-10
10. What is the semi-major axis of this ellipse in AU? ______________
11. What is the perihelion distance of this orbit in AU _______________
12. What is the aphelion distance of this ellipse in AU? ______________
13. What is the eccentricity of this ellipse? ____________
14. The asteroid 1620 Geographos discovered on September 14, 1951 at the Palomar Observatory by
Albert George Wilson and Rudolph Minkowski.. Its orbital semi-major axis is 1.24 AU. What is its
orbital period in days? Show your work to solve the problem below.
15. The same asteroid 1620 Geographos has an eccentricity of 0.34. What is its perihelion distance? Why
would this asteroid be of special concern for astronmers?
16. Please choose one of Galileo’s telescopic observations of the Moon, the Sun, or Jupiter and briefly
describe what he saw and how it contradicted the Aristotelian Model of the Universe. Be complete in
your answer. Answer in a few sentences.
17. The figure below is a reproduction of Galileo’s record of observations of Venus from Il Saggiatore
[The Assayer] Rome, 1623. What is it about Galileo’s Venus observations that was so damaging to the
Aristotelian/Ptolemaic Model of the Universe? Answer in a few sentences.
18. The Universal Gravitational constant G is an extremely small number equal to 6.6710-11 in mks units.
What does it mean that G is so small? What would the universe, or daily life, be like if G were a
number closer to one? Answer in a few sentences below.
19. If Neptune was 1.0 A.U. from the Sun (instead of 20 A.U.), would the gravity force between Neptune
and the Sun be less or more than it is now? By how many times?
20. A star designated as BD +48 738 is known to have a planet orbiting it. The mass of the planet is about
289 Earth masses and orbits exactly 1.00 AU from the star. The mass of the star is 0.74 times the mass
of the Sun. Which of the statements below regarding the time this planet takes to orbit the star true?
Circle the correct answer.
a.
b.
c.
d.
The planet takes one year to circle the star because it is 1 AU from it.
The planet takes longer than one year to circle the star because it is so massive.
The planet takes less than one year to circle the star because it is so massive.
The planet takes longer than one year to circle the star because the star is less massive than the
Sun.
e. The planet takes less than one year to circle the star because the star is less massive than the Sun.
The figure below shows four identical stars and four planets of various masses in circular orbits of various
sizes. In each case the mass of the planet is given in Earth masses and the orbital distance is given in
Astronomical Units (AU). Note that the sizes of the stars and the orbital distances have not been drawn to
scale.
21. Which of the following is the best possible ranking for the period of the orbit of these planets orbiting
from shortest to longest?
Two Earth Masses
One Earth Mass
Three Earth Masses
1 AU
A
C
A
One Earth Mass
2 AU
1 AU
2 AU
C
B
D
D
B
a.
b.
c.
d.
e.
D<C<B<A
A = C < B =D
A=B<C<D
A < C < B <D
A=B=C=D
22. The image to the right is of an asteroid named Ida and its tine satellite
named Dactyl (That’s right – an asteroid with a moon!) What would and
astronomer need to know about this Ida-Dactyl system to calculate the
mass of the asteroid Ida? Answer in a few sentences.
23. An asteroid is observed by a student astronomer with their
telescope. The asteroid is at opposition on January 1 and
then again at opposition exactly 15 months later. See the
figure. Calculate the orbital period of the asteroid in
years.
1st Opposition



2nd Opposition
1. The Moon appears to cycle around the zodiac once every________.
A. 365.25 days
D. 24 hours
B. 29.5 days
E. 23 hours 56 minutes
C. 27.3 days
2. Which of the statements below about the apparent path of the Moon through the stars is the true
statement?
A. The Moon drifts eastward through the stars on the ecliptic following the path of the Sun.
B. The Moon’s path through the stars is westward along the ecliptic completing once cycle every
365.25 days.
C. The Moon’s path through the stars is eastward closely following the ecliptic, but the Moon does
not return to exactly the same place in the sky after one sidereal period as the Sun does.
D. The Moon’s path through the stars is generally eastward, but is interrupted by occasional
retrograde motion.
3. Put the phases of the Moon in chronological order, from earliest to latest, starting with waxing crescent.
A
B
Earliest: ______,
C
______,
______,
D
______,
E
______ : Latest
4. Lunar phase today is Waning Crescent. The moon is in the zodiac sign Cancer.
A. Approximately how days from today to the next Full Moon? __________
B. Approximately how many days from today will the Moon again be in the zodiac sign of
Cancer?_________
5. The sketch to the right shows the Moon in a certain phase.
A. Name the phase of the Moon shown. __________ ___________
B. Estimate the number of days till the next
Full Moon
_______________ Days
C. Circle the position of the Moon on the diagram below that corresponds to the phase shown
above.
Sun Light
Earth
6. The position of the Sun and Moon are show on the 360 Mercator view of the sky below.


12 hrs
8 hrs
4 hrs
0 hrs
20 hrs
16 hrs
12 hrs
A. In what phase would the Moon be seen in given its position in the map above?
____________
________________
B. Label the approximate position of the Sun in 8 months from the position shown.
C. Label the approximate position of the Moon in 3 weeks from the position shown.
7. The Moon is shown near setting in the image below. The line to the left is the celestial equator and the
upper line is the ecliptic. The gray bar represents the horizon.
A. In what constellation did the Moon rise earlier? ______________________
B. Where along the horizon die the Moon rise earlier? (Circle the correct response below)
N of E,
S of E,
due E,
N of W,
S of W or due W
C. In what constellation will the Moon set on the next day? _____________________
8. In a few sentences below define the lunar sidereal period and the
lunar synodic period and explain why they are different time
periods. You may refer to the figure to the right in your
response.
9. Circle the seven planets of the ancient world from the alphabetic list presented below.
Earth
Jupiter
Mars
Mercury
Moon
Neptune
Pluto
Saturn
Sun
Uranus
Venus
10. In one sentence describe how these “planets” appeared to be different from all the other stars. (Two
differences are required for full credit)
11. Which of the times listed below represents the average apparent sidereal period of Mars?
A. 365.25 days
D. 29 years
B. 687 days
E. 250 years
C. 12 years
12. Which of the angles listed below represents the maximum elongation of Venus?
A. 23½ 
C. 45
B. 28
D. 180
13. Which of the statements listed below best represents the apparent relationship between the Sun and the
Superior Planets?
A. The Superior Planets are never seen at opposition to the Sun.
B. The Superior Planets have a maximum elongation and appeared “tied” to the Sun.
C. The Superior Planets only go retrograde when in opposition to the Sun.
D. The Superior Planets only go retrograde when in conjunction to the Sun.
14. In the figure below label the positions of a planet at opposition, conjunction, quadrature and maximum
elongation. The position of the Earth (  ) and Sun (  ) are shown on the figure.


15. Use the graph provided below, on which an imaginary planet’s motion has been plotted over several
months, to answer the next question.
May 15th
Path of the
imaginary
planet
March 21st
April 22nd
March 1st
March 31st
April 12th
April 5th
80
100 120
140
160 180 200
60
55
50
45
40
35
30
25
20
15
10
5
220 240 260
16. For how many days would this planet have appeared to move with retrograde motion?
A. 10 days
A) 17 days
B. 12 days
B) 32 days
C. 15 days
Use the two images below, which were obtained from the Solar Heliospheric Observer (SOHO) spacecraft, to
answer the following question. The Sun is located behind the circle drawn on the mask and the bright object to
the right is a planet. The images were taken approximately four days apart with the earlier picture on top.
Eastward
Westward
Image obtained on May 12
Image obtained on May 16
17. The planet is approaching which of the planetary configurations listed below?
A. Maximum Elongation
C. Opposition
B. Conjunction
D. Quadrature
18. Which of the statements listed below could ONLY be the planetary configuration known as
conjunction? (This question is tricky – sketch out the options if you have too.)
A. The Earth and the Sun are on the same side of the planet.
B. The Earth and the planet are on the same side of the Sun.
C. The Sun and the planet are on opposite sides of the Earth.
D. The Earth and the planet are on opposite sides of the Sun.