Final Exam Chapters 1-24 and 30
If there is a full Moon out tonight, approximately how long from now will it be in the third quarter phase?
1 week
Express 10,000,000 in standard scientific notation.
1.0 ´ 107
If you observe a maximum number of sunspots right now, how long would you have to wait to see the next solar maximum?
11 years
In the figure, at which position must the Moon be located in order for a lunar eclipse to occur?
4
At a latitude of +50°, how far above the horizon is the north celestial pole located?
50°
To measure the parallax of the most distant stars measurable, we would make two measurements of the star's position on the sky separated by
6 months
Roughly what percentage of stars in our galaxy are main-sequence stars?
90 percent
Why do O- and B-type stars have weaker hydrogen absorption lines than A-type stars?
A larger fraction of hydrogen atoms in O- and B-type stars is ionized.
What is differentiation?
A process by which gravity causes heavier elements to sink to the center of a planet.
What is a pulsar?
A rapidly rotating magnetic neutron star
In the figure, a planet orbits the Sun. The line connecting the planet and Sun sweeps out three areas labeled A, B, and C, during three different time intervals. If the duration of the time intervals are the same (meaning t2 - t1 = t4 - t3 = t6 - t5), how are the sizes of these areas related?
A, B, and C have the same size.
Why do astronomers search for black holes using x-ray telescopes?
Accretion disks around black holes are hot enough to emit x-ray radiation.
What happens as a protostar contracts? a. Its density rises. b. Its temperature rises. c. Its radius decreases. d. Its pressure rises. e. All of the above are true.
All of the above are true.
Which giant planets have rings?
All of them
Which of the following is NOT a result of the conservation of angular momentum?
All of these are caused by the conservation of angular momentum.
Which of the following cannot be determined by a star's spectrum?
All of these can be determined from a star's spectrum.
Which of the following cannot be determined by a star's spectrum? a. The physical size of the star b. The rotational speed of the star c. The composition of the star d. All of these can be determined from a star's spectrum.
All of these can be determined from a star's spectrum.
Which of the following statements about supernovae is false?
All supernovae are caused by the core collapse of massive stars.
In which scenario is a non-zero net force acting on the object?
An ice skater skates in a circle at a constant speed.
What is the difference between apparent brightness and luminosity?
Apparent brightness is how much light we see from a star; luminosity is how much light it emits.
Where would you find a red giant on an HR diagram?
At low temperature and high luminosity
Where would you find an M-type main sequence star on an HR diagram?
At low temperature and low luminosity
Why is crater counting an imperfect measure of a terrestrial planet's age?
Because it can change
Why is a solar day longer than a sidereal day?
Because the Earth orbits the sun, the sun's position in the sky changes, requiring the Earth to rotate farther in order for the sun to return to the same position.
What do astronomers believe is at the center of every galaxy?
Black hole
Blackbody A peaks at a longer wavelength than Blackbody B. What can we say about the temperature and color of Blackbody A compared to Blackbody B?
Blackbody A is cooler and redder than Blackbody B.
In the figure, a planet orbits the Sun. During which of the three sections (A, B, or C) will the planet have the lowest average velocity?
C
The giant planets all have: a. strong winds. b. ring systems. c. all of the above d. strong magnetic fields.
C
Why are most modern telescopes reflecting telescopes? a. Reflecting telescopes do not suffer from chromatic aberration. b. It is easier to make mirrors of a high enough quality than it is to make lens of the same quality. c. All of these are reasons astronomers favor reflecting telescopes. d. Reflecting telescopes are easier to build compactly.
C
The polar caps of Mars are primarily composed of solid:
CO2.
Unlike Earth, the atmospheres of Venus and Mars are primarily composed of:
Carbon Dioxide
If the mass of a white dwarf exceeds 1.4 solar masses, it will explode as a Type Ia supernova. This mass value is known as the:
Chandrasekhar limit
You observe three different star clusters and find that the main-sequence turnoff stars in Cluster 1 have spectral type F, the main-sequence turnoff stars in Cluster 2 have spectral type A, and the main-sequence turnoff stars in Cluster 3 have spectral type G. Which star cluster is the youngest and which one is the oldest?
Cluster 2 is the youngest and Cluster 3 is the oldest.
Cluster A contains 1 red giant, a handful of O-, B-, and A-type stars, and many F-, G-, and M-type stars. Cluster B contains a handful of red giants, 2 A-type stars, and many F-, G-, and M-type stars. Which cluster is older?
Cluster B
Which of the following methods of energy transport is NOT important in the Sun?
Conduction
A net force must be acting when an object a. accelerates. b. changes direction but not speed. c. changes speed but not direction. d. all of these are correct.
D
Below are four proposals for new telescopes. Which proposal is the BEST one to fund? (a) An x-ray telescope on a mountain top in New Mexico (b) A visible light telescope near Norman, OK (c) An ultraviolet telescope near the North Pole (d) A radio telescope in the Mojave Desert
D
Which of the following is NOT a way that general relativity has been confirmed? a.General relativity successfully predicts observed changes in Mercury's perihelion. b.Astronomers have observed the deflection of starlight by the Sun during a solar eclipse. c. GPS is able to accurately determine a person's location on Earth. d. All of these have been used to confirm general relativity.
D
The process by which gravity helps separate a planet's interior into layers of different compositions and densities is called:
Differentiation
How is the distance to a star related to its parallax?
Distance is inversely proportional to parallax.
The terrestrial world most similar to Mercury is:
Earth's Moon.
There is an angle between the ecliptic and the celestial equator because
Earth's axis is tilted with respect to its orbit.
The main reason we experience seasons is because
Earth's equator is tilted relative to the plane of the solar system.
Leap years occur because
Earth's orbital period is 365.24 days.
A lunar eclipse occurs when __________ shadow falls on __________.
Earth's; the Moon
What type of binary system can be used to determine the radius of a star?
Eclipsing binary
Why do the giant planets have stronger magnetic fields than terrestrial planets?
Giant planets rotate faster than terrestrial planets.
__________ tend to contain older, more evolved stars, while __________ tend to contain younger stars.
Globular clusters; open clusters
Which evolve faster, high mass stars or low mass stars, and why?
High mass stars; they have higher fusion rates due to their higher core temperatures
What critical event transforms a protostar into a normal main-sequence star?
Hydrogen fusion begins in the core.
Where are elements heavier than iron formed?
In supernova explosions.
Why does stellar fusion in massive stars end with an iron core?
Iron does not produce energy when it undergoes fusion.
Why is Pluto no longer considered a planet?
It has not cleared its orbit of smaller bodies.
How does the greenhouse effect change the habitability zone of a star?
It moves the zone outward.
How do astronomers find the masses of stars in a binary system?
Kepler's Third Law
A comet having an orbit of 50 years would likely have come from the
Kuiper Belt.
Scientists refer to a well-developed model that has been tested many times in many different ways as a:
Law
Which of the following correctly orders the spectral types of stars from coolest to hottest?
MKGFABO
What is the primary reason main sequence stars have such a large range of temperatures?
Mass
Which of the following statements about geological activity is false?
Mercury is a geologically active planet.
Mercury is primarily made of:
Metals
Before the Kepler mission, why were the majority of known exoplanets giant planets?
Methods of finding exoplanets are more effective at finding larger planets.
Stars form in what region of the ISM?
Molecular clouds
An astronomer takes a spectrum of a nearby star. She finds that its absorption lines all appear at shorter wavelengths than expected from laboratory measurements. She should conclude that the star is:
Moving toward her
A rocket engine accelerates its exhaust gas in one direction, moving the rocket in the other direction. Which law explains this phenomenon?
Newton's third law
What relationship allows astronomers to easily calculate distances for Cepheid variable stars?
Period-luminosity relationship
Which of the following observations provided the most direct challenge to the geocentric model of solar system orbits?
Phases of Venus
Which of the following is a consequence of Kepler's 2nd Law?
Planets have higher orbital speeds closer to the Sun and slower orbital speeds farther from the Sun.
Why do astronomers typically search for signs of intelligent life in radio wavelengths?
Radio waves are better at penetrating dust and gas than shorter wavelengths.
Ptolemy's formulation of the geocentric model provided the first successful set of predictions for the:
Retrograde motion of the planets
The radial velocity method is best at detecting exoplanets with ___________ orbital radii and ___________ planetary masses.
Small; large
Which of the following is the biggest disadvantage of putting a telescope in space?
Space telescopes are much more expensive than similar ground-based telescopes.
Why are about 90% of the stars we observe on the main sequence?
Stars spend most of their life on the main sequence
You are shopping for telescopes online. You find two in your price range. One of these has an aperture of 20 cm, and the other has an aperture of 30 cm. If aperture size is the only difference, which should you choose, and why?
The 30 cm, because the light-gathering power will be better.
How to astronomers currently believe the Moon formed?
The Earth was struck by a large asteroid, and the resulting debris came together to form the Moon
Solar eclipses are rare because:
The Moon's orbit around the Earth is tilted with respect to the Earth's orbit around the Sun.
Which of the following statements about tidal forces is true?
The Moon's tidal force is stronger than the sun's tidal force.
Astronomers find a new comet with a period of 987 years. Where did this comet likely come from?
The Oort Cloud
Why do some stars in the sky appear blue, whereas other stars appear red?
The blue stars have higher surface temperatures than the red stars.
Why are molecular clouds the only regions in the ISM where complex molecules can form?
The dust in molecular clouds protects complex molecules from being destroyed by ultraviolet radiation.
During the final core collapse of a massive star, the outer layers of the star are destroyed by:
The enormous amount of energy carried away by neutrinos
How would the force of gravity change if the mass of the Earth AND the distance between the Earth and Sun were BOTH doubled?
The force would decrease.
How would the strength of the force between the Moon and Earth change if the mass of the Earth were made two times greater than its current mass?
The force would double
In general relativity, light follows a curved path because:
The gravitational force of an object warps spacetime, affecting the path of light passing through space near the object.
Why are some moons such as Io and Enceladus geologically active even though they are small in size compared to the planets?
The interiors of these moons are heated by the rapidly changing direction and strength of tidal forces from Jupiter, resulting in geological activity
Solar activity is primarily caused by
The magnetic field of the Sun
Why do the outer giant planets have massive gaseous atmospheres of hydrogen and helium whereas the inner planets do not?
The outer planets grew massive quickly enough to gravitationally hold on to these gases before the solar wind dispersed the accretion disk.
For a certain atom, the energy difference between the lowest energy level and the first excited level is 3 arbitrary units. What happens to an electron in the lowest energy level if we shine a beam of photons with an energy of 2 units on the atom?
The photon will not be absorbed.
Which of the following provides the BEST evidence that Mars once had large amounts of liquid water?
The presence of runoff and outflow gullies on its surface
What is the proton-proton chain?
The process by which a star fused 4 hydrogen atoms into 1 helium atom
What is accretion?
The process by which planetesimals grow by attracting nearby planetesimals.
Astronomers see hydrogen lines is a star at longer wavelengths than they see them in a laboratory. What can astronomers infer solely from this information?
The star is moving away from us.
Why does the spectrum of an O-type star look different than the spectrum of an M-type star?
The stars have different temperatures.
Why did the giant planets accrete so much hydrogen and helium, while the terrestrial planets did not?
The terrestrial planets did not grow massive enough to hold on to those gases before the solar winds blew them out of the disk.
Why are pulsars periodic?
Their radiation sweeps across Earth periodically.
Which of the following statements is false?
There is no evidence of water on the Moon
When a star burns hydrogen in a shell, how does the energy released compare with when the star burned hydrogen in the core?
There will be more energy produced.
Why do astronauts feel "weightless" inside the International Space Station?
They are "falling" along the same orbit as the space station.
Why are sunspots dark?
They are cooler than their surroundings.
What influence do pairs of shepherd moons have on the giant planets' rings?
They keep rings between the pair narrow by gravitational tugs on the ring particles.
Why is it difficult to observe the process of star formation?
They occur in dusty regions and the star formation process happens so quickly
Which of the following is not a result of mass transfer in binary star systems?
Type II supernovae
Uranus and Neptune are different from Jupiter and Saturn in that
Uranus and Neptune have a higher percentage of ices in their interiors.
Why does the Moon have phases?
We observe different amounts of the lit and dark sides of the Moon as it orbits the Earth.
What is the difference between weather and climate?
Weather refers to short term changes, while climate refers to changes that occur over centuries.
You hear a news story about an X-ray telescope being built on Earth. You know this can't be possible because
X-rays do not travel very far through Earth's atmosphere.
Pseudoscience refers to:
a belief or practice that is made to look scientific but that was not developed through the scientific method.
Astronomers discover a bright X-ray source in the Milky Way. They see no counterpart in the optical bands, but it has another star orbiting it, and they determine that the X-ray source has a mass of 10 MSun. What is the most likely origin of the X-rays?
a black hole
Meteor showers occur because Earth passes through the path of
a comet.
An iron meteorite most likely came from
a differentiated asteroid.
Which of the following photons carries the smallest amount of energy?
a microwave photon, whose wavelength is 10-2 m
When an electron moves from a higher energy level in an atom to a lower energy level,
a photon is emitted.
Which of the following is an important effect of interstellar dust?
a platform for the formation of molecules
The nuclei of a comet is mostly
a porous mix of ice and dust.
The Great Red Spot on Jupiter is
a storm that has been raging for more than 300 years.
When astronomers refer to "metals," which elements are they talking about?
all elements more massive than helium
Which of the following are created by solar magnetic activity? a. sunspots b.prominences c. coronal mass injections d. solar flares e. all of the above
all of the above
Which stars we see at night depends on a. our location on Earth. b. Earth's location in its orbit. c. the time of the observation. d. all of these answers are correct.
all of these answers are correct.
The orbits of the planets in our Solar System:
all proceed in the same direction.
Circumpolar stars are stars that are
always above the horizon.
If you observe an isolated hot cloud of gas, you will see
an emission spectrum.
Stars with a larger brightness must be a. closer to us than fainter stars. b. larger in size than fainter stars. c. intrinsically brighter than fainter stars. d. any combination of the above.
any combination of the above.
The temperature of an object has a very specific meaning as it relates to the object's atoms. A high temperature means that the atoms
are moving very fast
When we observe a star that is 10 light-years away, we are seeing that star
as it was 10 years ago.
If scientists want to find out about the composition of the early Solar System, the best objects to study are
asteroids and comets.
Where on Earth can you stand and, over the course of a year, see the entire sky?
at the equator
Very young star clusters have main-sequence turnoffs
at the top left of the main sequence.
When you look at the visible surface of a gas giant planet, you are looking at that planet's
atmosphere.
As a comet leaves the inner Solar System, the ion tail points
away from the Sun.
Why does Jupiter radiate more energy than it receives from the Sun?
because it is still contracting under its own gravity
What is the final stage of stellar evolution for a 50 solar mass star?
black hole
Light has aspects of
both a particle and a wave.
An object that is hot enough to fuse deuterium but not hydrogen is called a:
brown dwarf
An iron core cannot support a massive main-sequence star because iron
cannot fuse to make heavier nuclei and produce energy.
When a cup of coffee cools through rising and falling motions of the fluid, we say it undergoes:
convection.
The hottest layer of the solar atmosphere is the
corona.
Which of the following is NOT a region found in the interstellar medium?
coronal winds
Earth's magnetic field is created by:
currents in the outer core.
Cameras that use adaptive optics provide higher-spatial-resolution images primarily because
deformable mirrors are used to correct the blurring due to Earth's atmosphere.
What mechanism provides the internal pressure inside a neutron star?
degeneracy pressure from neutrons
The Sun's internal magnetic field becomes tangled up over time because of
differential rotation.
A light-year is a measure of
distance.
Our understanding of Earth's interior comes primarily from
earthquakes
What supports a white dwarf star against gravity?
electron degeneracy pressure
When Earth catches up to a slower-moving outer planet and passes it in its orbit, the planet
exhibits retrograde motion.
According to the theory of relativity, a clock on top of Mount Everest would run _______ compared with a clock at sea level because _________________________________ .
faster; of the high altitude, which means a slightly weaker gravity
Which of the following lists different types of electromagnetic radiation in order from the shortest wavelength to the longest wavelength?
gamma rays, ultraviolet, visible, infrared, radio waves
Which of the following is a key constituent of the interstellar medium?
gas and dust
Why does Jupiter gives off more energy than it receives from the Sun?
gravitational contraction
The equivalence principle says that is a sufficiently local environment, we cannot experimentally distinguish between:
gravity and acceleration
The general theory of relativity includes an explanation of:
gravity and space-time.
Where do stars form in molecular clouds?
high-density cores.
A protostar's evolutionary "track" in the H-R diagram traces out
how the protostar's luminosity and temperature change with time.
The majority of the Sun's energy comes from
hydrogen fusion.
The balance between pressure and weight is known as
hydrostatic equilibrium
On a typical H-R diagram, where are the stars with the largest radii located?
in the upper right corner
As the energy of light increases, the frequency _____________ and the wavelength _____________.
increases; decreases
Arrays of radio telescopes can produce much better resolution than single-dish telescopes because they work based on the principle of
interference.
The collapse of the core in high-mass stars naturally explains all but which one of the following neutron stars properties?
large distance from Earth
The spectroscopic radial velocity method preferentially detects
large planets close to the central star.
Scientists look for water to indicate places where life might exist because
life on Earth depends on it.
The Hertzsprung-Russell diagram is a graph of _________ for stars.
luminosity versus temperature
What determines the location of a star on the main sequence?
mass
What are two ways that Type Ia supernovae can be produced?
mass transfer and stellar mergers
Which of the following phases of the interstellar medium is coldest?
molecular clouds
Galileo's telescopic observations of the _________ led him to conclude that the heliocentric model of the Solar System was correct.
moons of Jupiter and phases of Venus
The difference between a moon and a planet is that
moons orbit planets, whereas planets orbit stars.
What carries the bulk of the energy from the gravitational collapse of a massive star's core during a supernova?
neutrinos
The physical model of the Sun's interior has been confirmed by observations of
neutrinos and seismic vibrations.
What stops the collapse of the most massive stars at the end of their lives?
nothing
The Drake equation estimates the:
number of technologically advanced civilizations in the Milky Way.
In the simplest form of the scientific method, which of the following correctly describes the sequence in which science proceeds?
observation, hypothesis, experiment
The Moon probably formed
out of a collision between Earth and a Mars-sized object.
Which of the following lists astronomical distance measurement techniques in order (from nearest to farthest) of the maximum distance to which they are useful?
parallax, spectroscopic parallax, Cepheid variables, Type Ia Supernovae
Kepler's third law is a relationship between an orbiting object's
period and semimajor axis.
The fact that the speed of light is constant as it travels through a vacuum means that
photons with longer wavelengths have lower frequencies.
The oxygen in Earth's atmosphere was first created 2.3 billion years ago by:
photosynthesis.
Detecting a planet around another star using the transit method is difficult because the
planet must pass directly in front of the star.
Arrange the following objects in order of increasing size:
planet, star, galaxy, galaxy cluster, supercluster.
Hot Jupiters provide evidence for:
planetary migration.
Dust reddens starlight because it
preferentially affects light at visible and shorter wavelengths.
When the core of a massive star collapses, a neutron star forms because
protons and electrons combine to make neutrons.
The period between pulses from a particular pulsar increases slowly with time. This implies that the:
pulsar's radiation is powered by energy from the pulsar itself.
What wavelength regime is most commonly used in searches for extraterrestrial intelligence?
radio
If we know the temperature and luminosity of a star, we can also calculate its
radius.
Gravitational waves are:
ripples in the fabric of space-time.
Asteroids are small
rock and metal objects orbiting the Sun.
Which of the following most directly provides the energy source for extreme weather on the giant planets?
rotation
Because angular momentum must be conserved, as a gas cloud contracts due to gravity it will also
spin faster.
Newton's first law states that objects in motion
stay in motion unless acted upon by an unbalanced force.
The solar magnetic field
switches polarity every 11 years.
The spectral class of a star is related to its
temperature
A star's position in the H-R diagram is determined by its
temperature and size.
When a boat moves through the water, the waves in front of the boat bunch up, while the waves behind the boat spread out. This is an example of
the Doppler effect.
We always see the same side of the Moon because
the Moon rotates on its axis once for each revolution around Earth.
Solar and lunar eclipses are rare because
the Moon's orbital plane is tipped by 5.2° relative to Earth's orbital plane.
A long line of active volcanoes often marks:
the boundary of two plates
Tides are caused by:
the differential gravity of the Moon and Sun.
Dust grains form within a protoplanetary disk because:
the disk cools through radiation.
Material withing a circumstellar disk initially clumps together when:
the disk cools through radiation.
What is the habitable zone?
the distance from a star where liquid water can exist on the surface of the planet
Scientists know that Earth was once completely molten because
the interior layers are denser.
Energy is produced primarily in the center of the Sun because
the outer parts have lower temperatures and densities.
What is the most important factor in determining whether or not a planet will be rocky like terrestrial planets or gaseous like giant planets?
the planet's distance from the Sun
The event horizon of a black hole is defined as
the radius at which the escape speed from the black hole equals the speed of light.
Degenerate matter is different from normal matter because as the mass goes up,
the radius goes down.
Studies of the amount of cratering at different locations on the Moon indicate that
the rate of cratering in the Solar System has changed dramatically over time.
We detect neutral gas in the interstellar medium by looking for radiation at 21 cm that arises when
the spin of an electron flips and aligns with the spin of a proton in a hydrogen atom.
Post-main-sequence stars lose up to 50 percent of their mass because
the star swells until the surface gravity is too weak to hold material.
Binary star systems are extremely useful in studying stars because they allow us to determine
the stars' masses.
Nuclei of atoms are held together by
the strong nuclear force.
At present, conclusions about extraterrestrial life are based on:
the study of life on Earth.
The most massive stars have the shortest lifetimes because
the temperature is higher in the core, so they burn their fuel faster.
The terrestrial planets and the giant planets have different compositions because
the terrestrial planets formed closer to the Sun.
The differences in the climates of Venus, Earth, and Mars are caused primarily by
the thickness of their atmospheres.
Helium fusion occurs via _________ which produces _________.
the triple-alpha reaction; carbon
The interior zones of the Sun are distinguished by
their modes of energy transport.
Photons have no mass, and Einstein's theory of general relativity says
their paths through spacetime are curved in the presence of a massive body.
Congress tasked NASA with searching for near-Earth objects because
they might impact Earth, as others have in the past.
Light is increasingly redshifted near a black hole because
time is moving increasingly slower as viewed from the observer's frame of reference.
The orbits of gas giants can move after their formation because of:
transfer of angular momentum from the planet to the surrounding gas.
As a star becomes a red giant, how does it move on the HR diagram?
upward and to the right
What is "spectroscopic parallax"?
using stellar spectra to measure distances
Which of the following is most strongly affected by interstellar dust?
visible light
Dust in the ISM appears dark in _________ wavelengths and bright in _________ wavelengths.
visible; infrared
Which of the following has most strongly shaped Venus's surface?
volcanism
The fact that no alien civilizations have yet been detected indicates that
we don't know enough yet to draw any conclusions.
Most large irregular moons probably formed
when passing objects were captured by the gravitational field of their planet.