Unit 2 of astronomy
What method was used to land the Mars Pathfinder spacecraft successfully on the Martian surface?
It was surrounded by balloons, similar to the airbags in automobiles, and allowed to bounce and roll to a stop, after impact on the planet.
What appears to be the "impact history" of cratering on the Moon?
an early period of heavy bombardment followed by a decrease in intensity (except for a spike around four billion years ago) and then very light bombardment to the present
The Tharsis rise on Mars, a region that is higher than the surrounding plain by about 5 km (over 16,000 ft), was caused by
an upwelling magma plume in Mars' interior, which has raised this whole region.
The lunar maria appear smooth because they are
ancient lava flows that occurred soon after the end of an early period of intense bombardment and that have had relatively few impacts since then
The sulfuric acid clouds on Venus
are confined to a narrow layer about 60 km above the planet's surface and cover the whole planet.
On Earth, you would expect to find metamorphic rocks
at the boundaries of colliding tectonic plates, where upthrust has brought them to the surface.
The lunar maria are composed of which of the following rock types?
basalt
The terminator on the Moon is a line
between the solar-illuminated and dark hemispheres.
At temperatures hotter than the freezing point of water, light gases, like hydrogen and helium, likely had too much energy to condense together to form the large, gas-giant, Jovian planets. Over what range of distances from the Sun would you expect to find light gases, like hydrogen and helium, collecting together to form a Jovian planet?
beyond 50 AU *incorrect*
Most of the mountain ranges on the Moon are the
circular edges and rims of large maria, caused by impacts from large objects.
Moon rocks contain no water in their crystal structure and contain far less volatile material than those on Earth. Which theory of the origin of the Moon provides the most likely explanation for these differences?
collision of a large meteoroid with Earth and the ejection of very hot material, depleted in volatiles, into orbit around Earth
The motions of large portions of Earth's surface, or "plates," are caused by
convective flow of matter in Earth's interior.
The main characteristics of our solar system are
four small planets close to the Sun and four large planets far from the Sun
The mass of the planet Jupiter is high and its atmosphere is relatively cool. What are the chances for the retention of gases within its atmosphere?
good for all gases, including light (H2 and He) and heavier (CH4, NH3, H2O) molecules
Most of the craters on the Moon were created by
impacts of rocky debris during the first billion years of the Moon's history.
The birthplace of the Sun and planets (and of other stars and maybe their planets) is thought to have been
in cool gas and dust clouds.
A typical asteroid is (See Figure 7-7 of Universe, 10th ed.)
potato shaped with large and small craters.
Hot-spot volcanism is a process that
produces gigantic volcanoes on Venus and Mars but produces chains of smaller volcanoes on Earth (e.g., the Hawaiian Islands).
Which one of the following processes was important for melting the entire Earth about 4.6 billion years ago?
radioactivity, or the spontaneous breaking apart of heavier nuclei into lighter nuclei
Radioactive decay is...
random process happening all around you all of the above something we can find useful producing decay products
The best images of the overall topology of Venus have been produced by
reflection of microwave and short radio wave radiation from the surface by an orbiting spacecraft.
The Van Allen belts are
regions of high-energy charged particles trapped within Earth's magnetosphere
In order to produce a planet-wide magnetic field, a planet must have in its interior some material capable of carrying the electric current in such a way as to produce a dynamo effect. All of the following substances appear to be able to fill this role, except one. Which is the exception?
solid iron
What phenomenon causes the V-shaped patterns that are a prominent feature on Venus?
strong winds blowing from east to west, combining with north-south convection currents at cloud altitudes
At the present time, how many extrasolar planets have had confirmed discoveries?
thousands
The circulation in Earth's atmosphere is dominated by
three large convection cells in each hemisphere, with surface winds toward the equator in the tropics and away from the equator at temperate latitudes.
What is the primary cause of moonquakes?
tidal forces due to the gravitational pull of Earth
The discovery of nitrogen gas (N2) in the atmosphere of Titan was made by
ultraviolet spectroscopy from Earth.
Over what range of distances from the Sun would you expect to find solid, rocky material collecting together to form a terrestrial planet?
0 - 0.2 AU *incorrect*
The timescale over which material in the solar nebula accreted to form planets was about
100 million years.
What is the approximate age of the oldest rocks brought back from the Moon by astronauts during the Apollo program?
4.3 billion years
Our solar system seems to have formed about how long ago?
5 billion years
What was the temperature at the location of Mars?
500 K
Consider the information provided in the graph and table below. The graph shows the temperature (expressed in Kelvin) at different distances from the Sun (expressed in Astronomical Units, AU) in the solar system during the time when the planets were originally forming. The table provides some common temperatures to use for comparison. What was the temperature at the location of Earth?
700 K
The major constituents of the atmosphere are
77% nitrogen and 21% oxygen
A sample of fossilized bone is C14 dated. The original amount of C14 in the plant matter was 5,000,000 atoms. Currently there are 1,250,000 C14 atoms. How old is the fossil?
About 11,460 years.
A sample of fossilized bone is C14 dated. The original amount of C14 in the plant matter was 5,000,000 atoms. Currently there are 625,000 C14 atoms. How old is the fossil?
About 17,190 years.
The Viking Lander spacecraft measured a steadily decreasing atmospheric pressure soon after landing on Mars. What was found to be the cause of this observation?
Atmospheric CO2 was freezing out into "dry ice" as colder temperatures signaled the onset of the Martian winter.
Which is hotter, the piece of mantle material at Position A or the piece of mantle material at Position D? Why?
D. This is closest to the nuclear fusion in the core, which is what produces Earth's heat. *incorrect*
What direction are the pieces of mantle material moving at Position B?
Down
When Mercury is seen 18° from the Earth-Sun line, it will be visible a little less than an hour after sunset. What is the most important value in determining this time?
Earth's rotation period about its axis
The Australia-India tectonic plate (See Figure 9-13 of Universe, 10th ed.) is pushing against which plate to form the Himalayan Mountains?
Eurasian Plate
Consider the following statements made by two students debating why the oceanic and continental plates move. Student 1: The plates are moving because the mantle material is constantly moving beneath Earth's plates, and this causes the plates to move. Student 2: I disagree. The plates are just floating on the mantle material. The plates stared moving a long time ago when Earth initially formed and the plates' momentum keeps them moving toward each other. Do you agree or disagree with either or both of the students?
I agree with Student 1
Consider the image below of the rocky and crater-covered Moon. Its very old surface has remained virtually unchanged over the last few billion years. Do you think the Moon has an active, hot, and molten interior or an inactive, cold, and solid interior?
Inactive, cold, and solid interior
Billions of years ago, Earth's atmosphere was composed primarily of carbon dioxide. What happened to much of this carbon dioxide?
It dissolved into Earth's oceans.
What is surprising about the planet orbiting the star 51 Pegasi?
It has a mass almost as large as Jupiter, but its orbital radius is smaller than that of Mercury.
One of the major differences between Earth and its neighboring planets, Venus and Mars, is the lack of large quantities of CO2 in its atmosphere. If all three planets were originally formed with significant quantities of this gas in their atmospheres, where is the majority of this CO2 on Earth at the present time?
It is locked up in carbonate and carbon-rich rocks and minerals formed in the sea and on Earth's surface.
What is the status of the greenhouse effect on Mars at the present time?
It is very weak and raises the planet's temperature only a few degrees above the temperature it would have with no atmosphere at all.
Just beneath point I on the drawing is a tropical island. What will eventually happen to the island as the oceanic plate moves? Why?
It will collide with the continental plate, becoming part of a large mountain. *incorrect*
Just beneath point C on the drawing is an ancient impact crater on the ocean floor where a giant comet collided with Earth. What will happen to the ancient impact crater as the oceanic plate moves? Why?
It will subduct with the oceanic plate under the continental plate.
How big is Ceres, the largest asteroid?
Its diameter is about the length of California.
Suppose that observers using the Hubble Space Telescope detect around several solar-type stars the presence of planets with the following characteristics: low density; large size; polar diameters shorter than equatorial diameters; fluid surfaces; and rapid rotation. How would these planets be classified in terms of our solar system?
Jovian planets
The average density of which of the following planetary groups is close to that of water (1000 kg/m3)?
Jovian planets, because of their H and He composition
Which is the largest planet in our solar system?
Jupiter
Which planets formed at temperatures cooler than the freezing point of water?
Jupiter, Saturn, Uranus, Neptune
The region outside the orbit of Neptune in which a large number of objects composed of rock and ice circle the Sun not far from the plane of the ecliptic is called the
Kuiper belt.
In general, large bodies in the solar system show less evidence of cratering than do small bodies. Why should we expect this correlation?
Large bodies cool more slowly and are more likely to retain internal heat and be geologically active, capable of resurfacing the planet and obliterating craters.
In the drawing above, which way (right or left) is the continental plate moving?
Left
What direction are the pieces of mantle material moving at Position C?
Left
What type of search technique has discovered the largest number of planets around the stars other than the Sun?
Looking for tiny variations in the star's radial velocity, caused by the gravitational pull of one or more planets orbiting the star.
The asteroid belt exists between the orbits of which planets?
Mars and Jupiter
Which one of the following planets shows the greatest amount of cratering on its surface?
Mercury
Why does Venus experience fewer transits of the Sun than does Mercury?
Mercury is closer to the Sun and thus orbits more frequently.
Which planets formed at temperatures hotter than the boiling point of water?
Mercury, Venus, Earth, Mars
Mercury's orbital period around the Sun is 88 days, and its synodic period (the time from one inferior conjunction to the next) is 116 days. How often do we observe a transit of Mercury across the face of the Sun?
Much less frequently than once every 116 days because Mercury's orbit is inclined 7° from the plane of the ecliptic.
Table 7-2 describes the seven largest satellites in the solar system. From these data it can be seen that the presence of an atmosphere correlates with
None of the above
Is it likely that a large, Jovian planet would have formed at the location of Mercury?
No. A large Jovian planet only forms where it is cold enough for ices to help build planets.
On Mars, the air pressure varies much more from one season to another than it does on Earth. Why is this?
On Mars, much of the CO2, the major constituent of the atmosphere, condenses out to the surface as snow. This gas is only a minor constituent in Earth's atmosphere.
The impact craters on Earth are younger than a few million years old, whereas ages of lunar craters extend back billions of years. Why is this?
Plate tectonics has erased older craters on Earth, whereas this process has not occurred on the Moon.
The extremely high temperature of Earth's core causes material in the surrounding mantle to become hot, expand, and rise toward the surface. The mantle material then cools and sinks, resulting in a circular motion of material moving beneath Earth's surface. Thihs circulation of mantle material causes the continental and oceanic plates to move across Earth's surface. At various locations on Earth's surface, we are able to observe plates colliding, plates separating, and plates moving horizontally. The drawing below shows a cross section of Earth's surface and its underlying mantle. At this particular location of the surface, the dense oceanic plate is being forced beneath the less dense continental crust. The dense oceanic plate experiences higher temperatures (and pressures) as it is forced deeper into the mantle. This interaction between the oceanic plate and continental plate causes molten material to move upward through the continental plate until it breaks the surface in the form of volcanoes. ***In the drawing above, which way (right or left) is the oceanic plate moving?****
Right
What direction are the pieces of mantle material moving at Position A?
Right
The most probable time sequence for the solar system's formation was that the
Sun contracted first as a gas ball, and the planets and moons formed shortly afterward by accretion and condensation.
Which of the following statements is a correct description of the rotation of Earth?
The average length of a day is gradually getting longer because Earth's rate of rotation is slowing down.
We have found that the upper layers of the mantle are "plastic." Why is this important?
The continents are able to float and drift on these layers.
The Earth has an average density of 5500 kg/m3, whereas the density of rock on its surface is about 3000 kg/m3. What conclusion can be reached about the Earth's core from this observation?
The core is made of material far denser than surface rock.
Geologists land on a new planet and begin a series of seismic measurements. A quake occurs, and they detect both S and P waves on the opposite side of the planet from the quake. What does this say about the planet's geology?
The entire core must be solid.
Which of the following general statements about the Moon is true?
There is one side of the Moon from which Earth can never be seen.
The gases trapped in Earth's interior at its formation probably had the same abundances as the solar nebula. What happened to the light elements hydrogen and helium?
They escaped into space.
What direction are the pieces of mantle material moving at Position D?
Up
Volcanoes have been discovered on all of the following planets except one. Which one is the exception?
Uranus
Imagine that an impact occurred on the continental plate millions and millions of years ago, leaving behind an impact crater near the right side of the base of the volcano. Why would there be little evidence of this impact crater found today?
Volcanic eruptions over the years would have damaged or destroyed all traces of the crater.
Is there any correlation between the color of the Moon's surface material and the elevation at which it is found?
Yes, darker materials are generally found at lower elevations.
Based on its mean density, Pluto appears to be composed of
a mixture of rock and ice.
The Oort cloud is
a spherical solar system halo of icy objects far beyond the orbit of Pluto.
How long is a "lunar day," or the time between two successive sunrises or sunsets on the Moon?
about 1 month
The manner in which the terrestrial planets formed was
accretion of solid planetesimals containing mostly rocky material.
Viewed from a position above the north pole of the Sun, the directions of the motions of the planets in their orbits are all
counterclockwise.
Which one of the following is more or less uniform across the planets of the solar system?
direction of orbital motion around the Sun
The moons of Mars are
irregularly shaped, cratered, and grooved.
Despite the planet's close proximity to the Sun, water ice remains on the surface of Mercury because it
is permanently shielded from the Sun by crater walls at the north and south poles.
The temperature in the stratosphere increases with increasing altitude because
it is heated by the absorption of solar ultraviolet radiation by ozone.
Venus appears to be very bright in our skies at certain times because
it is relatively close to the Sun, Earth is close to it, and it is covered by very reflective clouds.
One consequence of the combination of rapid orbital motion and synchronous rotation of Phobos as it orbits Mars is that
it is slowly spiraling into the planet.
The mean density of a planet is
its total mass divided by its volume.
A regolith is a(n)
layer of pulverized rock on the surface of a planet or other object.
Which of the following signs of water is not seen on Mars?
melting pools at the edges of the polar caps
Earth's solid inner core results from the fact that the
melting temperature of the core material increases with increasing pressure and rises above the actual temperature in the inner core.
The wide absorption features in the optical spectrum of Titan's atmosphere (See Figure 7-3 of Universe, 10th ed.) are produced by
methane gas, CH4.
Sedimentary rocks commonly form from
minerals precipitating out of the oceans and accumulating on the ocean bottom.
Compared to earthquakes, moonquakes are
much weaker and less frequent, occurring mostly when the Moon is at perigee.
The Moon has
no global magnetic field, although weak magnetism in lunar rocks does show that a magnetic field existed earlier in the Moon's history.
Venus has
no magnetic field
A major feature of the atmosphere of Mars is
occasional strong winds and dust storms.
The type of rock making up the lunar highlands is
old, low-density rocks—anorthosite.
Earth's thermosphere is the
outermost atmospheric layer in which ultraviolet light from the Sun ionizes atoms.
The El Niño phenomenon refers to which natural pattern on Earth?
periodic warming of the equatorial Pacific Ocean surface
A molecule moves within the atmosphere of a planet. It would be less likely that this molecule would be retained in the atmosphere of this planet if the
planet's atmosphere were hotter.
What process heated the early solar nebula as it slowly condensed toward a central protosun?
release of heat by collisions of particles as they gain kinetic energy in falling toward the center of the nebula
The three common substances believed to have been important in planet formation are
rocks, ices, and gas.
The asteroid belt is made up of
rocky bodies from a few meters to hundreds of kilometers in diameter.
The waves that geologists and geophysicists use to probe the inside of Earth are
seismic waves.
We need the ozone layer because it
shields us from harmful solar ultraviolet radiation.
The overall shape of the orbits of most of the planets in the solar system is
slightly elliptical but nearly circular.
The process of accretion in planetary formation is the
slow accumulation of solid particles by gravity and collision into larger, solid objects.
One effect of the tidal drag of the ocean waters on Earth is to
slow down Earth's spin rate.
The trans-Neptunian objects (such as Pluto, Sedna, Quaoar, etc.) are
small worlds of rock and ice, most of which orbit within the Kuiper belt.
Suppose the Hubble Space Telescope discovers a series of planets with the following characteristics moving around a star resembling our Sun: spherical, solid surfaces; mean densities about four times that of H2O; radii about 4000 km; and low-density atmospheres. How would these planets be classified in terms of our solar system?
terrestrial planets
In general, a heavily cratered surface should imply a solid interior. Lack of a planet-wide magnetic field should also imply a solid interior. Which one of the following bodies actually possesses both a heavily cratered surface and no planet-wide magnetic field?
the Moon
The surface temperature of Earth is actually warmer than expected from the amount of sunlight received. This is a result of
the greenhouse effect.
In order to employ the radioactive age-dating technique on a sample of rock, it is necessary to know all of the following except one. Which is the exception?
the mass of the rock when it was formed
The temperature began to rise at the center of the solar nebula because
the nebula was contracting, increasing the speed of motion of the atoms.
What is the process of chemical differentiation?
the sinking of heavy material to the center of a planet or other object and the rising of lighter material toward the surface
Radioactive decay is
the spontaneous breaking apart, or decay, of unstable atomic nuclei
The protosun became a full fledged star when
thermonuclear fusion reactions began at its center
Detailed examination of the overall surface of the Moon and of the rocks brought back by Apollo astronauts reveals that
unlike Earth's rocks, there is no evidence of water locked into crystal structures in lunar rocks, but there are significant quantities of ice in cold lunar polar regions.
If a new planet were discovered, what evidence would you look for to determine whether or not it has an active, hot, and molten interior?
volcanoes
To an astronomer, the word "ice" can mean any one or more of
water (H2O), carbon dioxide (CO2), methane (CH4), or ammonia (NH3).
Mercury's magnetic field, compared with that of Earth, is
weak, but strong enough to deflect the solar wind.
