Astronomy Final- Jerome Fang OCC
What do we mean by the star-gas-star cycle?
A) It is the continuous recycling of gas in the galactic disk between stars and the interstellar medium.
Will our Sun ever undergo a white dwarf supernova explosion? Why or why not?
A) No, because it is not orbited by another star.
Imagine that our Sun were magically and suddenly replaced by a black hole of the same mass (1 solar mass). What would happen to Earth in its orbit?
A) Nothing; Earth's orbit would remain the same.
Why are collisions between galaxies more likely than collisions between stars within a galaxy?
A) Relative to their sizes, galaxies are closer together than stars.
Which of the following is an important starting assumption in models of galaxy formation?
A) Some regions in the universe start out denser than others.
Which of the following claims cannot be tested by science?
A) The Earth was created by God.
How does the Sun's mass compare to Earth's mass?
A) The Sun's mass is about 300,000 times the mass of the Earth.
If you are located in the Northern Hemisphere, which of the following correctly describes a 6) relationship between the sky and your location?
A) The altitude of the north celestial pole equals your latitude.
Why do scientists assume that the early universe was much hotter and denser than the universe of today?
A) The fact that the universe is expanding implies that objects were closer together in the past, and compressing material makes it hotter and denser.
Which of the following best describes why we have seasons on Earth?
A) The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year.
What do sunspots, solar prominences, and solar flares all have in common?
A) They are all strongly influenced by magnetic fields on the Sun.
What is the common trait of all main-sequence stars?
A) They generate energy through hydrogen fusion in their core.
Which of the following best describes the origin of ocean tides on Earth?
A) Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the Earth.
Suppose you drop a clock toward a black hole. As you look at the clock from a high orbit, what will you notice?
A) Time on the clock will run slower as it approaches the black hole, and light from the clock will be increasingly redshifted.
Which of the following statements about X-rays and radio waves isnot true?
A) X-rays travel through space faster than radio waves.
What do we mean by a geocentric model of the universe?
A) a model designed to explain what we see in the sky while having the Earth located in the center of the universe
If you had something the size of a sugar cube that was made of neutron star matter, it would weigh ________.
A) about as much as a large mountain
On a scale where the Sun is about the size of a grapefruit and the Earth is about 15 meters away, 10) how far away are the nearest stars besides the Sun?
A) about the distance across the United States
The ultimate fate of our Sun is to ________.
A) become a white dwarf that will slowly cool with time
From center outward, which of the following lists the "layers" of the Sun in the correct order?
A) core, radiation zone, convection zone, photosphere, chromosphere, corona
Lunar eclipses can occur only during a ________.
A) full moon
Collisions between galaxies typically unfold over a period of ________.
A) hundreds of millions of years
The main source of energy for a star as it grows in size to become a red giant is ________.
A) hydrogen fusion in a shell surrounding the central core
The Sun's location in the Milky Way Galaxy is ________.
A) in the galactic disk, roughly halfway between the center and the outer edge of the disk
After a supernova explosion, the remains of the stellar core ________.
A) may be either a neutron star or a black hole
Which of the following is not one of the three main strategies used to measure the mass of a galaxy clusters?
A) measuring the temperatures of stars in the halos of the galaxies
White light hitting white paper is an example of
A) reflection or scattering.
Our solar system consists of ________.
A) the Sun and all the objects that orbit it
What do we call the bright, sphere-shaped region of stars that occupies the central few thousand light-years of the Milky Way Galaxy?
A) the galaxy's bulge
What do we mean when we talk about theMilky Way in our sky?
A) the patchy band of light that outlines theplane of the Milky Way Galaxy as seen from Earth
An astronomical unit (AU) is ________.
A) theaverage distance between Earth and the Sun
The most basic difference between elliptical galaxies and spiral galaxies is that ________.
C) elliptical galaxies lack anything resembling the disk of a spiral galaxy
In terms of the "eras" that scientists use to describe different times in the history of the universe, we live in the __________.
C) era of galaxies
What two physical processes balance each other to create the condition known as gravitational equilibrium in stars?
C) gravitational force and outward pressure
The total amount of power (in watts, for example) that a star radiates into space is called its ________.
C) luminosity
Which of the following best summarizes what we mean by dark matter?
C) matter that we have identified from its gravitational effects but that we cannot see in any wavelength of light
The great contribution of Tycho Brahe was to ________.
C) observe planetary positions with sufficient accuracy so that Kepler could later use the data to discover the laws of planetary motion
Approximately where is it currently high tide on Earth?
C) on the portion of Earth facing directly toward the Moon and on the portion of Earth facing directly away from the Moon
How long does it take the Earth to complete one orbit around the Sun?
C) one year
In essence, the nebular theory holds that ________.
C) our solar system formed from the collapse of an interstellar cloud of gas and dust
Place the following items in order of actual physical size, from smallest to largest.
C) planet, star, solar system, galaxy
The interstellar clouds called molecular clouds are ________.
C) the cool clouds in which stars form
Which of the following observations cannot be explained by the Big Bang theory unless we assume that an episode of inflation occurred?
C) the fact that the temperature of the cosmic microwave background is almost the same everywhere
We cannot see a new moon in our sky because ________
D) It causes the seasons to be more extreme than they would be if the Earth's distance from the Sun were always the same.
Which of the following best summarizes what we mean by dark energy?
D) It is a name given to whatever is causing the expansion of the universe to accelerate with time.
What is the celestial sphere?
D) The celestial sphere is a representation of how the entire sky looks as seen from Earth.
Astronomers can measure a star's mass in only certain cases. Which one of the following cases might allow astronomers to measure a star's mass?
D) The star is a member of a binary star system.
Why do sunspots appear dark?
D) They are regions that are significantly cooler than the rest of the photosphere.
Our textbook discusses the cosmic calendar, a model of the history of the universe scaled to a 4) single year. The length of time represented by one month on this cosmic calendar is therefore-
D) about ten million years.
A typical white dwarf is ________.
D) as massive as the Sun but only about as large in size as Earth
Why are astronauts weightless in the Space Station?
D) because the Space Station is constantly in free-fall around the Earth
Stars that are visible in the local sky on any clear night of the year, at any time of the night, are called ________.
D) circumpolar
Which of the following types of galaxies appear reddest in color?
D) ellipticals
Which of the following types of material can condense into what we call ice at low temperatures?
D) hydrogen compounds
Which forms of light are lower in energy and frequency than the light that our eyes can see?
D) infrared and radio
According to the theory that active galactic nuclei are powered by supermassive black holes, the high luminosity of an active galactic nucleus primarily consists of ________.
D) light emitted by hot gas in an accretion disk that swirls around the black hole
Scientific models are used to ________.
D) make specific predictions that can be tested through observations or experiments
The mass of Jupiter can be calculated by
D) measuring the orbital period and distance of one of Jupiter's moons.
What do astronomers mean by theBig Bang?
D) the event that marked the beginning of the expansion of the universe
The force of gravity is an inverse square law. This means that, if you double the distance between two large masses, the gravitational force between them
D) weakens by a factor of 4.
If the Earth's rotation axis were tilted by 45 degrees instead of 23.5 degrees, what are some of the 8) implications, and why?
B) The seasons would be more extreme, because the Sun's rays would be more direct in summer, and less direct in winter.
Which of the following best describes the fundamental difference between two different chemical elements (such as oxygen and carbon)?
B) They have different numbers of protons in their nucleus.
Where does most star formation occur in the Milky Way Galaxy?
B) in the spiral arms
All of the statements below are true. Which one gives the primary reason why the surface of Venus today is some 450°C hotter than the surface of Earth?
Venus has a much stronger greenhouse effect than Earth.
Which of the following is an example of convection?
Warm air expanding and rising while cooler air contracts and fall.
What do we mean when we say that the terrestrial worlds underwent differentiation?
When their interiors were molten, denser materials sank toward their centers and lighter materials rose toward their surfaces.
The Huygens probe took numerous pictures as it descended to Titan's surface in 2005. What did the pictures show?
features or erosion, including what appeared to be dry river valleys and lakebeds
Based on all we know about the terrestrial worlds, what single factor appears to play the most important role in a terrestrial planet's geological destiny?
its size
What atmospheric constituent is responsible for the blue color of Uranus and Neptune?
methane
In essence, the Kepler mission searched for extrasolar planets by ____________.
monitoring stars for slight dimming that might occur as unseen planets pass in front of them
Which of the following best describes the lunar maria?
relatively smooth, flat plains on the Moon
If we have a new moon today, when we will have the next full moon?
B) in about 2 weeks
The fundamental nuclear reaction occurring in the core of the Sun is ________.
B) nuclear fusion of hydrogen into helium
What is the primary form of evidence that has led astronomers to conclude that the expansion of the universe is accelerating?
B) observations of white dwarf supernovae
Galileo challenged the idea that objects in the heavens were perfect by ________.
B) observing sunspots on the Sun and mountains on the Moon
When considering light as made up of individual "pieces," each characterized by a particular amount of energy, the pieces are called ________.
B) photons
Pulsars are thought to be ________.
B) rapidly rotating neutron stars
What is the Big Bang theory?
B) the idea that all matter and energy in the universe began in an unimaginably dense state, and then space itself began expanding
Most stars in the Milky Way's halo are ________.
B) very old
Ptolemy was important in the history of astronomy because he ________.
C) developed a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries
The two most important processes in heating the interiors of the terrestrial worlds are:
(1) Heat deposited by the process of formation; (2) heat released by radioactive decay.
What star is the most likely to have made the atoms of gold in your jewelry or your electronics?
B) a high-mass star
Suppose we use a baseball to represent Earth. On this scale, the other terrestrial worlds (Mercury, Venus, the Moon, and Mars) would range in size approximately from that of _________.
A golf ball to a baseball
What is an extrasolar planet?
A planet that orbits a star that is not our own Sun
The Big Bang theory is supported by two major lines of evidence that alternative models have not successfully explained. What are they?
A) (1) The theory predicts the existence of and the specific characteristics of the observed cosmic microwave background; (2) the theory correctly predicts the observed overall chemical composition of the universe.
What is the temperature of the universe (as a whole) today?
A) 3 K
What do astronomers mean by aconstellation?
A) A constellation is a region in the sky as seen from Earth.
Suppose you view the solar system from high above Earth's North Pole. Which of the following statements about planetary orbits will be true?
A) All the planets orbit counterclockwise around the Sun.
When we say that a cluster of galaxies is acting as a gravitational lens, what do we mean?
A) It bends or distorts the light coming from galaxies located behind it.
Why is Newton's version of Kepler's third law so useful to astronomers?
A) It can be used to determine the masses of many distant objects
How does Earth's varying distance from the Sun affect our seasons?
A) It doesn'tEarth's orbital distance plays no significant role in the seasons.
Which of the following is not a general difference between a planet and a star?
B) All planets are made of rock, and all stars are made of gas.
Which statement about the cosmic microwave background is not true?
B) It is the result of a mixture of radiation from many independent sources, such as stars and galaxies.
Which type of star spends the shortest time as a main sequence star?
B) O star
Which of the following is not part of a good scientific theory?
B) A scientific theory cannot be accepted until it has been proven true beyond all doubt.
From hottest to coolest, the order of the spectral types of stars is ________.
B) OBAFGKM
According to our present theory of solar system formation, which of the following statements about 18) the growth of terrestrial and jovian planets is not true?
C) The jovian planets began from planetesimals made only of ice, while the terrestrial planets began from planetesimals made only of rock and metal.
What kind of object do we think lies in the center of the Milky Way Galaxy?
C) a 3 to 4 million solar mass black hole
According to current scientific estimates, when did the Big Bang occur?
C) about 14 billion years ago
The mass of a supermassive black hole thought to power a typical bright active galactic nucleus is roughly ________.
C) 1 billion solar masses
According to modern scientific dating techniques, approximately how old is the solar system?
C) 4.5 billion years
Why is iron significant to understanding how a supernova occurs?
C) Iron cannot release energy either by fission or fusion.
What do we mean by the event horizon of a black hole?
C) It is the point beyond which neither light nor anything else can escape.
Which of the following lists the planets of our solar system in the correct order from closest to 1) farthest from the Sun?
C) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Which of the following best sums up current scientific thinking about the nature of dark matter?
C) Most dark matter probably consists of weakly interacting particles of a type that we have not yet identified.
Sirius is a star with spectral type A and Rigel is a star with spectral type B. What can we conclude?
C) Rigel has a higher surface temperature than Sirius.
Which of the following best describes the internal layering of Jupiter, from the center outward?
Core of rock, metal, and hydrogen compounds; thick layer of metallic hydrogen; layer of liquid hydrogen; layer of gaseous hydrogen; cloud layer.
If your mass is 60 kg (kilograms) on Earth, what would your mass be on the Moon?
D) 60 kg
Which of the following statements best summarizes current evidence concerning dark matter in individual galaxies and in clusters of galaxies?
D) Dark matter is the dominant form of mass in both clusters and in individual galaxies
Which of the following statements about various stages of core nuclear burning (hydrogen, helium, carbon, and so on) in a high-mass star is not true?
D) Each successive stage lasts for approximately the same amount of time.
Kepler's second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that
E) a planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun.
The sketch above shows groups of stars on the H-R diagram, labeled (a) through (e); note that (a) represents the entire main sequence while (c) and (d) represent only small parts of the main sequence. Which group represents stars of the largest radii?
E) e
Which statement about Io is true?
It is the most volcanically active body in our solar system.
Which new idea has been added into our theory of solar system formation as a result of the discoveries of extrasolar planets?
Jovian planets can migrate from the orbits in which they are born.
How does the strength of Jupiter's magnetic field compare to that of Earth's magnetic field?
Jupiter's magnetic field is about 20,000 times as strong as Earth's.
Which of the following statements about the moons of the jovian planets is not true?
Most of the moons are large enough to be spherical in shape, but a few have the more potato-like shapes of asteroids.
Which of the following statements is not true about the planets so far discovered around other stars?
Photographs reveal that most of them have atmospheres much like that of Jupiter.
Overall, what do current data suggest about planetary types in other planetary systems?
Planets come in a wider range of types than the planets in our solar system.
Which of the following statements comparing the jovian interiors is not thought to be true?
They all have the same exact set of internal layers, though these layers differ in size.
Which of the following is not a general characteristic of the four jovian planets in our solar system?
They are higher in average density than are the terrestrial planets.
What do we mean by a runaway greenhouse effect?
a greenhouse effect that keeps getting stronger until all of a planet's greenhouse gases are in its atmosphere
Olympus Mons is ______.
a huge volcano on Mars
A terrestrial world's lithosphere is ________.
a layer of relatively strong, rigid rock, encompassing the crust and part of the mantle
What is the Great Red Spot?
a long-lived, high-pressure storm on Jupiter
What do we mean by a "hot Jupiter"?
a planet that is Jupiter-like in size but orbits very close to its star
What is a magnetosphere?
a region of space around a planet in which the planet's magnetic field can trap charged particles
Based on current data, about what fraction of stars have one or more planets?
at least about 70%
From center to surface, which of the following correctly lists the interior layers of a terrestrial world?
core, mantle, crust
Suppose you could float in space just a few meters above Saturn's rings. What would you see as you looked down on the rings?
countless icy particles, ranging in size from dust grains to large boulders
The processes responsible for virtually all surface geology are _________.
impact cratering, volcanisms, tectonics, and erosion
In the context of planetary geology, what do we mean by outgassing?
the release by volcanism of gases that had been trapped in a planetary interior
