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| the study of the origin, present structure, evolution, and destiny of the universe |
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| mathematical descriptions that try to explain how the universe began, how it is changing as time goes by, and what will happen to it in the future |
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| evolutionary and steady state |
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| the two types of basic types of cosmological models |
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| a phenomenon that is caused by shift in red wavelengths of moving objects in the galaxy |
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states that a galaxy's velocity of recession, v, is directly proportional.
v = Hd
This is a constant |
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| the universe is both homogeneous and isotropic |
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| 13.7 + 1% billion years ago our universe expanded rapidly from an infinitely hot, dense state and has been evolving since |
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| the universe will continue expand indefinitely |
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| predicts a continuing to expand indefinitely |
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| if gravity acts alone the universe will not expand forever, but will contract until all matter is crushed again into a hot, dense state |
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| universe will contract until all matter is crushed again into a hot, dense state |
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| perfect cosmological principle |
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| says the universe is the same everywhere on the large scale, at all times (Steady State Theory assumes this) |
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| the minimum average density of matter and energy required to make the universe flat |
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| dubbed dark energy, equivalent to a cosmic repulsion, may drive an ever accelerating expansion |
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| Cosmic background radiation |
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| thought to exist due to the Big Bang |
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| the size of the observable universe, and is equal to the speed of light divided by the Hubble constant, so c/H |
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| the study of the origin, distribution, evolution, and future of life in the universe |
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| the area where both Voyagers are currently and is considered the edge of our solar system |
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| searches the entire sky over a wide frequency range to detect strong signals |
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| high-sensitivity target search |
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| seeks weak signals originating near close stars like our Sun |
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| A teaspoon in a glass of water appears to be broken or bent at the water line because of |
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| 5. Which important characteristic of a telescope that is used for visual observations can be altered simply by changing the eyepiece? |
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| The General Theory of Relativity has been experimentally supported by |
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| observing shifts in star positions near the eclipsed Sun |
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| 7. The Andromeda spiral galaxy is about three million light years away. Therefore, |
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| we are seeing the galaxy as it was three million years ago. |
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| The famous equation E = mc2, which describes the potential energy content E of any given mass m, fully explains |
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| the mass losses in the Sun’s hydrogen fusion reactions, creation of particles having mass by the collisions of energetic photons, and mass losses in the uranium-fission reactions of powerplants |
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| One of the first persons known to conduct experiments to investigate natural phenomena such as the behavior of falling objects, as opposed to only thinking about them, was |
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| The distance of 0.001 m would be written in scientific notation as |
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| 15. Who mathematically derived Kepler’s three laws of planetary motion from the laws of universal gravitation and of the conservation of angular momentum? |
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| If you were standing on the Earth’s South Pole, the North Star (Polaris) would be |
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| The people responsible for preserving much ancient Greek, astronomical knowledge, refining it, and passing it on to the Europeans (which helped launch the Renaissance) were the |
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| A planet’s gravity will curve the paths of passing _____ that were originally moving in straight lines |
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| The celestial sphere is a model of the sky that astronomers (and the Voyager 4 computer program) use to compute the appearances of celestial phenomena. However, one error of this model, usually of no importance, is that all stars are taken to be equally |
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| A new, large optical telescope, such as the 10-meter diameter Keck I reflector in Hawaii, costs about as much money as |
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| Which word below best matches this definition: “An explanation for a fundamental natural phenomenon, based on physical law as currently understood, which has passed every experimental test thus far.”? |
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| A star with a right ascension of 3h 10m and a declination of +1* 10’ would be located very close to the |
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| You are watching a spaceship fly past you at a speed for which the Lorentz factor у (gamma) equals 2. You measure that the moving ship is 1000 m long as it passes abreast of you. The ship then stops and lands near you. You remeasure the stationary spaceship, and find that its length is actually |
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| Optics tells us that the smallest angle θ (in arcseconds) that a telescope of diameter d (in mm) can resolve is given by θ = 116/d. The OSU observatory’s telescope is about 600 mm in diameter. Therefore, θ for that telescope is about |
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| The famous mnemonic device, “Oh, be a fine girl (guy), kiss me!”, was devised at the beginning of the 20th century by Dr. Henry Norris Russell, a Princeton astronomer. It is used to recall the proper order of |
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| In class you viewed the light and spectrum from an incandescent light bulb connected to a variable-voltage power supply. As the voltage was increased to make the bulb’s filament hotter, the bulb’s light output and spectrum became |
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| Assume that four stars, of spectral types A, M, G, and O, are all on the main sequence. According to the mass-luminosity relation, the least massive of these is of spectral type |
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| On a Hertzsprung-Russell Diagram, ___ is the horizontal axis, while ___ is the vertical axis. |
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| A star’s proper motion is measured in units of ___ and is due to a star’s having a nonzero ___ relative to the Sun. |
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| arsec/yr, tangential velocity |
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| Relative to the Sun, nearby stars move with velocities of roughly |
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| When an electron in a hydrogen atom “falls” from a higher energy level to a lower energy level, the atom |
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| Sunspots appear dark because they are |
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| cooler than the photosphere |
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| 9. The tiny, solid particles called dust that are often mixed in with the gas between the stars are commonly composed of carbon or silicon, meaning that they are like ___ in composition, respectively |
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| Imagine a binary star that consists of two main-sequence stars, one green and the other orange. The green star is more massive than the orange one. Where is the binary’s center of mass located? |
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| 11. Which type of ground-based telescope can easily observe astronomical objects in the daytime as well as at night? |
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| 12. The total amount of energy radiated per second by a star can either be described in terms of its ___ in Watts, or by its ___, which is a unitless number that can be thought of as a ranking. |
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| luminosity, absolute magnitude |
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| Which color of light is characterized by the highest energy? |
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| Those features at the surface of the Sun which are reddish, up to 104 km tall, and almost look like giant blades of grass are called |
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| A continuous, synchrotron spectrum is emitted by astronomical objects such as radio galaxies that contain ___ spiraling in intense ___ fields. |
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| 17. The parallax angle of a star is observed to be 0.2 seconds of arc. By computing the reciprocal of this number, we find that its distance from us is |
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| Which of the following luminosity class suffixes refers to stars of the supergiant type? |
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| 21. When you determine the temperature of the Sun from its prominent optical spectrum, you are specifically measuring the temperature of its |
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| 22. The nearby stars are mostly main-sequence (MS) stars of spectral type M because M stars |
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| live longer than other MS stars, so their numbers accumulate. |
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| 23. The apparent magnitude a star would have if it were 10 pc from Earth is called its ___ magnitude. |
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| has an average temperature of about 100,000 K. |
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| In a supernova explosion, the outer layers of the star are ejected into space by the outwardly moving |
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| 2. Suppose that own a white dwarf star “weighing” 1.1 solar masses. You add enough material to the star to increase its mass to 1.2 solar masses. Because the white dwarf’s electrons are degenerate, it will ___ in diameter and the temperature of its electrons will ___ to support the star’s added weight. |
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| 4. You can estimate the mass of a distant spiral galaxy if you pick out a star near the edge of the galaxy’s disk, and can measure the star’s orbital speed (around the galaxy’s center) and the star’s |
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| distance from the galaxy’s center. |
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| 5. In the study of star clusters, it is reasonably assumed that the stars within a given cluster differ significantly from each other only in |
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| 6. The forces of gas pressure and of gravity are normally balanced at every point within a star. If, for some reason, the internal gas pressure decreases (for example, as the nuclear fuel in the core is exhausted), then the star will initially |
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| 7. Which of the following would be the best distance indicator for the most distant galaxies? |
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| The Doppler shifts of galactic spectra |
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| 8. If the Moon were to instantly turn into a black hole of the same mass, it would |
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| orbit the Earth as usual. |
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| 9. When stars leave the main sequence on the H-R diagram, their outer envelopes (layers) expand immensely, so these stars become both |
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| 10. A galaxy that looks like a perfectly symmetrical sphere would be given which code designation? |
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| 11. The probability of one’s galaxy colliding with another galaxy within the same cluster of galaxies is |
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| much higher than (a) [the same as that of two stars’ colliding within a galaxy] |
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| 12. The imaginary part of a non-rotating black hole that is spherical and whose radius equals the Schwarzschild radius, the radius at which the escape speed equals the speed of light, is the |
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| 13. Hypotheses about the production of light pulses and / or radio “beeps” by a pulsar all rely on the existence of ___ in the pulsar’s rotating ___ |
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| asymmetry, magnetic field |
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| 14. Population I stars are metal-rich, while Population II stars are metal-poor. In our own Milky Way Galaxy, |
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| Population I stars are found in the disk. |
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| 15. The reddening of starlight (the removal of shorter wavelengths) as it travels through our Galaxy to us is mainly due to the presence of ___ in the interstellar medium along the route of travel. |
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| 16. Supernova remnants emit large quantities of synchrotron radiation detectable at radio wavelengths. Therefore, we know that these remnants contain ___ |
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| 17. Which of the following might one not expect to see at some time around a star that is being “born”? |
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| rings of ice and cold dust perpendicular to the object’s equator. |
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| 19. The glowing bubble or “hourglass” of gas that cnstitutes a typical planetary nebula came from the |
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| outer layers of a dying, red-giant star. |
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| 20. The amount of fuel that a star has to “burn” is proportional to its mass, while the rate at which that star consumes its fuel is proportional to its luminosity. Therefore, a star’s fuel-burning lifetime is proportional to its |
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| mass divided by its luminosity. |
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| 21. What “holds up” a black hole against the inward force of gravity? |
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| 22. In the process called “electron capture” that leads to the explosion of the most massive stars, a proton and an electron are forced together to form a neutrino (electric charge zero, mass almost zero) and one ___. Hint: consider the conservation of electric charge. |
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| 23. Recurring nova explosions are possible in a binary star system whose primary star is a red giant and whose secondary star is a ___. The two stars must be close enough together for a mass to flow from the ___ to the other star. |
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| 24. Which of the following exists almost exclusively in the halo of the Milky Way? |
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| 25. A neutron star is a neutron-rich object about as massive as the Sun but which as small in diameter as |
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