Term
| In the asteroid impact theory of the extinction of the dinosaurs some 65 million years ago, the dinosaurs (and over half of all the other species on the earth at that time) died off largely because |
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Definition
| dust injected into the stratosphere from the impact absorbed visible light from the Sun, causing global temperatures to plummet. |
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Term
| A typical shooting star in a meteor shower is caused by a ________ entering the earth's atmosphere. |
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Definition
| pea-size (or smaller) particle from a comet |
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Term
| Why was the Shoemaker-Levy 9 impact so important to astronomers? |
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Definition
| It dredged up material that gave us our first direct look at Jupiter's interior composition |
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Term
| What part of a comet points most directly away from the Sun? |
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Definition
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Term
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Definition
| a fragment of an asteroid from the solar system that has fallen to the earth's surface |
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Term
| Why isn't there a planet where the asteroid belt is located? |
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Definition
| Gravitational tugs from Jupiter prevented material from collecting together to form a planet. |
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Term
| An icy leftover planetesimal orbiting the Sun is |
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Definition
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Term
| Why aren't small asteroids spherical in shape? |
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Definition
| The strength of gravity on small asteroids is less than the strength of the rock. |
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Term
| Comets with extremely elliptical orbits, like comets Hyakutake and Hale-Bopp, |
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Definition
| come from the Oort cloud. |
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Term
| Which of the following statements about comets and asteroids is true? |
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Definition
| Comets are balls of ice and dust. |
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Term
| The first planets around other Sun-like stars were discovered: |
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Definition
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Term
| What defines the habitable zone around a star? |
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Definition
| the region around a star where liquid water can exist on planetary surfaces |
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Term
| Stephen J. Gould said evolution is based on two undeniable facts and one inescapable conclusion. Fact 1 is that species produce more offspring then can possible survive (based on the limits of ecosystems). Fact 2 is that offspring posess variations in heretable traits. The inescapable conclusion is: |
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Definition
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Term
| The analysis of certain Martian rocks on Earth show that they contain |
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Definition
| tantalizing hints of life. |
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Term
| How do we think the "hot Jupiters" around other stars were formed? |
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Definition
| They formed as gas giants beyond the frost line and then migrated inwards. |
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Term
| In the search for extrasolar planets, gravitational tugs can be detected by measuring: |
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Definition
| Red shifting and blue shifting of the star |
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Term
| Why do some scientists think that Jupiter's existence may have been critical for life to evolve on Earth? |
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Definition
| It kicked out many comets from the inner solar system through gravitational encounters, thus ending the heavy bombardment phase of the solar system. |
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Term
| The earliest evidence for life on Earth dates to |
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Definition
| about 3.8 billion years ago. |
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Term
| Extrasolar planets can be detected through: |
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Definition
Answers 1 and 2 only.
Observing planets directly through images or spectra
Observing gravitational tugs exerted on the star by the orbiting plane |
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Term
| After Mars, the next most likely candidates for life in the solar system are |
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Definition
| the large moons of the jovian planets. |
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Term
| Imagine having a very powerful telescope through which you could vaguely observe an extrasolar planet. Using spectrosopy, which of the following would most strongly suggest the presence of life? |
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Definition
| Molecular oxygen (O2), which only persists in the presence of photosynthesis. |
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Term
| Generally speaking, what is (are) considered necessary for life anywhere in the universe? |
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Definition
Liquid water
Chemical reaction, sunlight, or some other energy source.
organic molecules or some other source of nutrients that can be used to build cells |
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Term
| Why are hydrothermal vents (black smokers) useful in the study of early life on earth? |
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Definition
The primary producers of life around these structures use chemosynthesis to obtain energy
They are found on the deep ocean floor, which would have been a location protected from sterilizing uv radiation on the earth's surface
Prokaryotic archaea are living there in modern times, but their genetic material indicates they are evolutionarily ancient |
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Term
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Definition
assumes some individuals will possess traits that make them live longer
a particular environment cannot support 100% of the offspring that individual organisms produce
organisms best adapted for the conditions of a particular environment will thrive
the individuals that are most successful in a given environment will have at least some offspring with the same traits that made them successful |
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Term
| In 1974, a radio message was sent out from the Arecibo observatory in Puerto Rico. How far has it gotten, approximately? |
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Definition
| just a miniscule fraction of the distance across the Milky Way |
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Term
| On a Hertzsprung-Russell diagram, where would we find stars that have the largest radii? |
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Definition
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Term
| Which of the following characteristics of stars has the greatest range in values? |
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Definition
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Term
| The overall fusion reaction by which the Sun currently produces energy is |
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Definition
|
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Term
| The spectral sequence sorts stars according to |
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Definition
| 70 percent hydrogen, 28 percent helium, 2 percent other elements |
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Term
| What observations characterize solar maximum? |
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Definition
| We see many sunspots on the surface of the Sun. |
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Term
| What do we mean when we say that the Sun is in gravitational equilibrium? |
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Definition
| There is a balance within the Sun between the outward push of pressure and the inward pull of gravity. |
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Term
| Why are Cepheid variables so important for measuring distances in astronomy? |
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Definition
| Their luminosity can be inferred from their period. |
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Term
| Suppose you measure the parallax angle for a particular star to be 0.1 arcsecond. The distance to this star is: |
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Definition
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Term
| Which of the following is true about low-mass stars compared to high-mass stars? |
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Definition
| Low-mass stars are cooler and less luminous than high-mass stars. |
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Term
| Since all stars begin their lives with the same basic composition, what characteristic most determines how they will differ? |
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Definition
| Mass they are formed with. |
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Term
| A star's luminosity is the |
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Definition
| total amount of light that the star radiates each second. |
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Term
| At the center of the Sun, fusion converts hydrogen into |
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Definition
| helium, energy, and neutrinos. |
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Term
| Hydrogen fusion in the Sun requires a temperature (in Kelvin) of |
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Definition
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Term
| Which of the following statements about apparent and absolute magnitudes is true? |
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Definition
The magnitude system that we use now is based on a system used by the ancient Greeks over 2,000 years ago that classified stars by how bright they appeared.
A star with apparent magnitude 1 is brighter than one with apparent magnitude 2.
A star's absolute magnitude is the apparent magnitude it would have if it were at a distance of 10 parsecs from Earth.
The absolute magnitude of a star is another measure of its luminosity. |
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Term
| From the center outward, which of the following lists the "layers" of the Sun in the correct order? |
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Definition
| core, radiation zone, convection zone, photosphere, chromosphere, corona |
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Term
| Which of the following is closest in size (radius) to a neutron star? |
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Definition
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Term
| What types of stars end their lives with supernovae? |
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Definition
| stars that are at least several times the mass of the Sun |
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Term
| What did Carl Sagan mean when he said that we are all "star stuff"? |
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Definition
| that the carbon, oxygen, and many elements essential to life were created by nucleosynthesis in stellar cores |
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Term
| Which of the following is closest in size (radius) to a white dwarf? |
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Definition
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Term
| Which of the following sequences correctly describes the stages of life for a low-mass star? |
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Definition
| protostar, main-sequence, red giant, white dwarf |
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Term
| After a supernova event, what is left behind? |
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Definition
| either a neutron star or a black hole |
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Term
| Compared to the star it evolved from, a red giant is |
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Definition
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Term
| From an observational standpoint, what is a pulsar? |
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Definition
| an object that emits flashes of light several times per second or more, with near perfect regularity |
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Term
| When does a star become a main-sequence star? |
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Definition
| when the rate of hydrogen fusion within the star's core is high enough to sustain gravitational equilibrium |
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Term
| Compared to the star it evolved from, a white dwarf is |
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Definition
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Term
| What is the basic definition of a black hole? |
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Definition
| any compact object from which the escape velocity is greater than the speed of light |
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Term
| What do we mean by the singularity of a black hole? |
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Definition
| D) It is the center of the black hole, a place of infinite density where the known laws of physics cannot describe the conditions. |
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Term
| What are the two key observational facts that led to widespread acceptance of the Big Bang model? |
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Definition
| the cosmic background radiation and the high helium content of the universe |
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Term
| What makes up the interstellar medium? |
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Definition
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Term
| What kinds of objects lie in the halo of our galaxy? |
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Definition
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Term
| What kinds of atomic nuclei formed during the era of nucleosynthesis? |
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Definition
| hydrogen and helium and trace amounts of lithium, beryllium, and boron |
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Term
| What is the diameter of the disk of the Milky Way? |
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Definition
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Term
| Which of the following types of galaxies are most spherical in shape? |
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Definition
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Term
| What happened to the quarks that existed freely during the particle era? |
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Definition
| They combined in groups to make protons, neutrons, and their antiparticles. |
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Term
| Why do we expect the cosmic background radiation to be almost, but not quite, the same in all directions? |
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Definition
| The overall structure of the universe is very uniform, but the universe must have contained some regions of higher density in order for galaxies to form. |
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Term
| The disk component of a spiral galaxy includes which of the following parts? |
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Definition
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Term
| What is the major difference between an elliptical galaxy and a spiral galaxy? |
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Definition
| An elliptical galaxy lacks a disk component. |
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Term
| Which of the following is true about irregular galaxies? |
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Definition
| They were more common when the universe was younger. |
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Term
| Currently, we have direct experimental evidence on the behavior of matter and energy well enough to describe generally what was happening in the universe ________ after the Big Bang. |
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Definition
| 10^ -10 (ten to the minus tenth) second |
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