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Astronomy 1 S’16 Exam 2
Name_____________________
Identify terms (1 pt. each)
Label each term with the appropriate letter of a definition listed
1.Liquid metallic
hydrogen
2. Magnetosphere
3. Asteroid
4. Galilean Moons
5. Galileo Spacecraft
6. Cassini Spacecraft
7. Dwarf Planet
C
8. Gravitational collapse
N
I
D
G
L
P
A
9. comet
10. Kuiper belt
11. half – life
12. solar nebula theory
13. protoplanet
14. extrasolar planet
O
H
Q
E
M
K
15. absolute visual
magnitude
16. parsec
17. H-R diagram
18. Main sequence
19. Binary star
20. stellar parallax
S
F
R
T
B
J
A. A body that orbits the sun, is not a satellite of a planet, is massive enough to pull itself into a spherical
shape but not massive enough to clear out other bodies in and near it’s orbit
B. Pair of stars that orbit around their common center of mass.
C. A form of hydrogen that is a good electric conductor.
D. Small rocky world. Most orbit between Mars and Jupiter.
E. Theory that planets form in rotating disks of gas and dust around young stars.
F. The distance at which one astronomical unit subtends an angle of one arcsecond, equal to about 3.26
light-years
G. The four largest moons of Jupiter—Io, Europa, Ganymede, and Callisto
H. A region of the solar system beyond the orbit of Neptune, believed to contain many comets, asteroids, and
other small bodies made largely of ice.
I. The region of space surrounding an astronomical object in which charged particles are controlled by that
object's magnetic field
J. The apparent shift of position of any nearby star (or other object) against the background of distant
objects.
K. A planet that orbits a star other than the Sun
L. An unmanned spacecraft that studied the planet Jupiter and its moons, as well as several other Solar
System bodies.
M. A large body of matter in orbit around the sun or a star and thought to be developing into a planet.
N. The condensing of an astronomical object due to the influence of its own gravity,
O. A celestial object consisting of a nucleus of ice and dust and, when near the sun, a “tail” of gas and dust
particles pointing away from the sun.
P. A NASA/ESA/ASI mission to explore the Saturnian system
Q. The time required for the amount of something to fall to half its initial value.
R. A graph of stars showing the relationship between the stars' absolute magnitudes or luminosities versus
their spectral classifications or effective temperatures.
S. The measure of intrinsic brightness of a celestial object.
T. A series of star types to which most stars belong, represented on a Hertzsprung–Russell diagram as a
continuous band extending from the upper left (hot, bright stars) to the lower right (cool, dim stars)
Multiple Choice 2 pts each
Identify the letter of the choice that best completes the statement or answers the question.
1. Both Jupiter and Saturn
a. Have liquid metallic hydrogen in their interiors
b. Have rings
c. Emit more energy than they absorb from the sun
d. All of the above
2. The ____ of a planet is the region around the planet where the magnetic field is able to deflect the
solar wind and other charged particles.
a. Magnetic deflection shield
b. Ion particle shield
c. Corona
d. Magnetosphere
3. The Roche limit is the
a. the minimum pressure at which metallic hydrogen can be produced
b. distance from a planet within which a planet can not hold itself together.
c. maximum temperature which can exist in Saturn’s atmosphere
d. The outer diameter of the Oort cloud
4. What causes the geological activity seen on some of the inner moons of Jupiter?
a.
b.
c.
d.
Constant collisions with space debris provide a power source for geological activity
The strong magnetic field of Jupiter heats the surface of the inner moons.
Tidal friction as a result of being so close Jupiter heats their interiors.
Solar radiation reflected of Jupiter's surface provides a power source for geological activity.
4. Which of these Galilean satellites is most geological active?
a.
b.
c.
d.
5.
a.
b.
c.
d.
e.
Io
Europa
Callisto
Ganymede
The Galilean satellites orbit
Jupiter
Saturn
Uranus
Neptune
All of the above
6. How do we know that the rings of Saturn are made of independently orbiting particles rather than
solid sheets of material? (hint: the image below shows the Doppler shift observed of the rings)
a. The inner and outer edges of the rings have different orbital periods (correct)
b. Meteoroids have been observed to pass through the rings
c. Large individual particles can be seen with voyager images
d. Solid sheets would reflect 100% of the sunlight reflecting on the sheets (I also gave credit for this)
7.
a.
b.
c.
d.
The rotation of Uranus is peculiar in that
It is very slow, nearly zero
It is much faster than is typical for Jovian planets
It first turns in one direction, the stops and turns in the opposite direction
The axis is nearly parallel to the plane of its orbit.
8.
a.
b.
c.
d.
Which of these Galilean moons is most likely to harbor extraterrestrial life?
Ganymede
Europa
Althea
Mimas
9. An extrasolar planet is a planet found orbiting around a star other than the sun. As of now we have
discovered
a. No extrasolar planets
b. 2 extra solar planets
c. Over 2000 extra solar planets
d. Many extra solar planets with alien life
10.
a.
b.
c.
d.
e.
The satellites discovered by Galileo
Orbit the planet Jupiter
Orbit the terrestrial planets
Orbit asteroids
Orbit mars
Orbit extrasolar planets
11. Which of the following planets was discovered because of its gravitational effect on the orbits of other
planets?
a. Jupiter
b. Saturn
c. Uranus
d. Neptune
12.
a.
b.
c.
d.
The age of the solar system is believed to be approximately 4.6 billion years based on the data from
Samples of lunar rocks
Samples of earth rocks
Sample of meteorites
All of the above
13. Protoplanets
a. Grew in size primarily by condensation
b. Are still visible today as terrestrial planets
c. Grew in size primarily by accretion
d. Grew in size by collecting particles in the solar wind
e. Grew in size by the collision and coalescing of planetesimals
14. How is radioactive dating used to determine the age of an object?
a. Both the amounts of radioactive and decay material are measured. Using these with the
radioactive material’s half-life, the age can be estimated
b. The amount of radioactive material is measured. Using this with the radioactive material’s half-life,
the age can be estimated.
c. The amount of decay material is measured. Using this with the radioactive material’s half-life, the
age can be estimated.
d. The amount of heat generated by radioactive dating is measured to determine age.
15.
Which of the following best describes the material which makes up the nucleus of a comet?
a. Rocky
b. gaseous
c. dirty ice
d. metallic crystals
16. The spacecraft which entered an orbit around Saturn in 2004 and sent a lander to Saturn’s moon,
Titan is
a. Vanera
b. New Horizons
c. Cassini-Hygens
d. Enterprise
____ 17. Parallax would be easier to measure if
a. Earth's orbit were larger. b. the stars were farther away. c. Earth moved faster along its orbit. d. all of
these e. none of these
____ 18. A star's luminosity depends only on the star's
a. distance and diameter.
b. temperature and distance.
c. distance.
d. temperature and diameter.
e. apparent magnitude.
____ 19. In an H-R Diagram, stars with the smallest
radius are found in the __________ of the
diagram.
a. center
b. upper left corner
c. upper right corner
d. lower left corner
e. lower right corner
______20. Betelgeuse is a cool, very bright red star in
the constellation of Orion. It is known as a supergiant.
Draw on the diagram where it would be found.
____ 21. Compared with the spectral lines in the solar
spectrum, lines in a supergiant spectrum are
a. more narrow. b. broader. c. weaker. d. stronger. e. b and c
____ 22. In a binary system, the more massive star
a. is at the center of mass.
b. is farthest from the center of mass.
c. is nearest the center of mass.
d. follows the largest orbit.
e. shows a larger Doppler shift in its
spectral lines.
23 .If two stars are emitting the same amount of light, the star that is farther will appear
a. brighter.
b. dimmer.
c. redder.
d. bluer.
e. They will have the same brightness as seen from Earth.
24..We can determine the surface temperature of a star from
a. studying its continuous spectrum.
b. studying its line absorption spectrum.
c. measuring the star's luminosity. (since all are correct, I gave credit for any of the choices)
25. A star with a luminosity of 104 has approximately
a. 1 solar mass
b. 5 solar masses
c. 20 solar masses
d. – 5 solar masses
Write a short essay on two of the following 3 topics:
1. How does the solar nebula theory explain the dramatic density difference between the Terrestrial
and Jovian planets?
The difference in the density of terrestrial and Jovian planets can be explained by the
different ability of materials (elements, molecules) to condense at a certain temperature
(condensation sequence). In the case of the terrestrial planets, the gas was so hot (since it
was near to the center of the system), that only matters with high “boiling points” were
able to condense. Therefore, only metals and then also silicates could condense to form
solids. At these inner orbits, material with lower boiling points (lighter elements) could not
be collected, since it still was in its gaseous state. This way the inner planets selectively
were made out of heavy elements and thus have now high densities. At greater distance
from the center, matter like water ice and methane ice could condense
and more and more pieces could stick together. Therefore, the Jovian planets started to
form from these icy grains consisting mostly of light elements. The Jovians contain both
heavy and light elements due to cooler temperatures of the outer solar system during its
formation but a much higher fraction of light elements since they were more abundant in
the primeval solar nebula. This is the reason why these planets have lower densities than
the terrestrial planets.
2.Discuss why astronomers no longer consider Pluto a planet.
This group decided that Pluto was not really a planet because of its size and location in space. So
Pluto and objects like it are now called dwarf planets. Pluto is also called a plutoid. A plutoid is a
dwarf planet that is farther out in space than the planet Neptune.
3.What observational evidence do we have that nebulae from which planets could form surround other stars?
Perhaps the most convincing line of evidence supporting this theory are observations of the same
process currently happening elsewhere in our Galaxy. It would be strange if our Solar System
formed in a different way to every other system in the Galaxy, since physics is supposed to work
the same way everywhere. We see stars forming in the depths of giant clouds of gas and dust, and
we even see young stars with disks of debris around them, which look just like the debris disk we
think the planets formed from.