ASTRO 101 FLASH CARDS MIDTERM

Term All stars appear as points of light, because	Definition They are so far away
Term The average distance from Earth to the Sun is	Definition 1 astronomical unit (AU)
Term The light year is a unit of	Definition Distance
Term In the scientific method, a hypothesis	Definition Must be tested through observation
Term An observer on the earth's North Pole would find	Definition Polaris directly overhead
Term The seasons on Earth are the result of	Definition The tilt in Earth's axis and its motion around the Sun
Term Which of the following phenomena is a result of Earth's rotation on its axis?	Definition The rising and setting of the Sun
Term The winter solstice occurs when the Sun	Definition Is at its lowest position at noon, when viewed by northern hemisphere observers
Term The phases of the moon are the result of the	Definition Motion of the moon around the earth and the relative positions of the moon, Earth, and Sun
Term When the moon is located between Earth and the Sun, the phase of the moon as seen from Earth is	Definition New
Term The circular shape of Earth's shadow on the moon led early astronomers to conclude that	Definition The earth is a sphere.
Term Eclipses of the Sun can occur only when the phase of the moon is	Definition New
Term Eratosthenes' method for determining the circumference of the earth was based on the observation of	Definition The Sun at two different locations
Term A planet in retrograde motion	Definition Shifts westward temporarily with respect to the stars
Term To account for some of the observed retrograde motion of the planets, Ptolemy's geocentric model required that the planets move in	Definition Small circles called epicycles
Term The Copernican heliocentric model explains retrograde motion by	Definition Earth motion passing the planet
Term The major contribution made by Copernicus that revolutionized the model of the heavens was	Definition The Sun is the center about which the planets and Earth move.
Term The success of Tycho Brahe is attributed to his ability to	Definition Make accurate observations with large and well-constructed instruments.
Term The Copernican model did not work perfectly, because it specified	Definition The planets move in uniform circular motions.
Term As discovered by Kepler, a planet moves in elliptical orbits and moves fastest in its orbit when it is	Definition Closest to the Sun
Term Galileo's observations of the gibbous phase of Venus proved that	Definition Venus went around the Sun, not Earth.
Term The observations of Galileo eventually led scientists to conclude that the	Definition It was produced by nuclear fusion in stars.
Term What is the ecliptic plane?	Definition The plane of Earth's orbit around the Sun.
Term If the moon is setting at 6 a.m., the phase of the moon must be	Definition Full
Term Which of the following statements about parallax is not true?	Definition The technique of stellar parallax was used by Hubble to determine that the Andromeda Galaxy (M31) is about 2 million light years away.
Term Suppose you are facing north and you see the Big Dipper close to your northern horizon with Polaris (and the Little Dipper) above it. Where will you see the Big Dipper in six hours?	Definition To the right of Polaris; this is, 90 degrees counterclockwise from its current position
Term How does Earth's varying distance from the Sun affect the seasons?	Definition It doesn't; Earth's orbital distance plays no obvious role in the seasons.
Term The names of the seven days of the week are based on	Definition The seven naked-eye objects that appear to move among constellations
Term Jupiter emits	Definition More infrared radiation than it receives from the Sun
Term The belts and bands of Jupiter are the result of atmospheric features that have been	Definition Stretched and elongated as a result of Jupiter's rapid rotation
Term The Great Red Spot on Jupiter is best described as	Definition A massive storm system in the upper atmosphere
Term Saturn and Jupiter have noticeable equatorial bulges due to	Definition Their rapid rotation and liquid interiors
Term The ring system of Saturn consists of	Definition Small particles of ice and rock
Term The rings of Saturn occupy a region near the planet where	Definition Tidal forces would break a large satellite apart
Term The low average densities of Jupiter and Saturn compared to Earth suggest what?	Definition They contain large quantities of light elements, such as hydrogen and helium.
Term What makes some astronomers think that Uranus was hit by a large body early in its history?	Definition It moves nearly at right angles to the orbital plane.
Term Planet Uranus appears blue because of	Definition Methane absorbing red light
Term The satellite system of Neptune is unique because	Definition The satellites' orbits are peculiar, as if they were disturbed long ago.
Term The small size and mass of Pluto was determined by observations of what?	Definition Its moon, Charon
Term The orbit of Pluto is	Definition So elongated that the planet sometimes moves closer to the Sun than Neptune
Term Why isn't Pluto considered a Jovian planet?	Definition Its mass and radius are small, and it lacks a thick atmosphere.
Term Which planet has the highest average surface temperature and why?	Definition Venus, because of its dense carbon dioxide atmosphere
Term Which is the densest planet in the solar system?	Definition Earth
Term Which of the following is not a characteristic of the outer planets?	Definition They have very few, if any, satellites.
Term What are the main constituents of the Jovian planets?	Definition Hydrogen and helium
Term The terrestrial planet cores contain mostly metal because	Definition Metals sank to the center during a time when the interiors were molten throughout.
Term What kind of surface features may result from tectonics?	Definition All of the above
Term From center to surface, which of the following correctly lists the interior layers of a terrestrial world?	Definition Core, mantle, crust
Term Why does the moon have a layer of powdery "soil" on its surface?	Definition It is the result of countless tiny impacts by small particles striking the moon.
Term What atmospheric constituent is responsible for the blue color of Uranus and Neptune?	Definition Methane
Term An icy leftover planetesimals orbiting the Sun is	Definition A comet
Term What characteristic distinguishes a meteorite from a terrestrial rock?	Definition All of the above
Term The asteroid belt is located	Definition Between the orbits of Mars and Jupiter
Term Why isn't there a planet where the asteroid belt is located?	Definition Gravitational tugs from Jupiter prevented material from collecting together to form a planet.
Term Why is the sky blue on Earth?	Definition Because gas molecules in the atmosphere scatter blue light more effectively than red light
Term Many scientists suspect that Venus has a stronger and thicker lithosphere than Earth. If this is true, which of the following could explain it?	Definition Venus has a much stronger greenhouse effect than Earth.
Term Which moon is considered likely to have a deep, subsurface ocean of liquid water?	Definition Europa
Term Kirkwood gaps in the asteroid belt are caused by	Definition Orbital resonances with Jupiter
Term When Newton said that gravitation was universal, he meant that	Definition It was a property of all matter in the universe.
Term According to Newton's law of universal gravitation, if the distance between two objects increases, the force of gravity between them will	Definition Decrease
Term A satellite launched into an orbit about the earth, far above the effects of the atmosphere and not acted upon by an outside force, will	Definition Continue to orbit Earth
Term What fundamental law of nature explains why planets move by Kepler's laws?	Definition Universal gravitation
Term The light from the center of a star passing through its cooler and thinner atmosphere produces a(n) __________ spectrum.	Definition Absorption (dark-line)
Term An astronomer finds that the visible spectrum of a mysterious object shows bright emission lines. What can the astronomer conclude about the source?	Definition It is a hot, relatively tenuous gas.
Term If two stars are the same size, but different temperatures, then the hotter star is	Definition Bluer and brighter
Term Which of the following stellar properties can be determined from a star's spectrum?	Definition All of the above
Term Place the following forms of electromagnetic radiation in order of decreasing wavelength, starting with the longest. Infrared Ultraviolet Radio waves Visible X-rays	Definition 3, 1, 4, 2, 5
Term The chemical element found in greatest abundance in all normal stars is	Definition Hydrogen
Term If a line in a star's spectrum shifts toward the red end of the spectrum, the star is	Definition Moving away
Term The main reason to increase the size of an optical telescope located on Earth is to improve	Definition Light-gathering power
Term The main advantage of space telescopes is they allow astronomers to	Definition Observe in wavelengths that cannot be observed from Earth
Term By linking several radio telescopes together electronically to create an interferometer, astronomers can	Definition Observe details better
Term Which of the following telescopes must be above Earth's atmosphere?	Definition An X-ray telescope
Term As long as an object is not gaining or losing mass, a net force on the object will cause a change in	Definition Velocity
Term At which lunar phase(s) are tides most pronounced (e.g. the highest high tides)?	Definition Both new and full moons
Term Why do astronomers need different telescopes designed to observe across the electromagnetic spectrum.	Definition Photons of different energy behave differently and require different collection strategies.
Term How does the light collecting power of an 8-meter telescope compare to that of a 2-meter telescope?	Definition The 8-meter telescope has 16 times the light-collecting area of the 2-meter telescope.
Term The spectra of most galaxies show redshifts. This means that their spectral lines	Definition Have wavelengths that are longer than normal
Term Suppose the Sun shrank in size but its mass remained the same. What would happen to the orbit of Earth?	Definition Earth's orbit would be unaffected.
Term The mass of Jupiter can be calculated by	Definition Measuring the orbital period and distance of Jupiter's orbit around the Sun
Term Which of the following observations indicated that conditions on Mars might have been suitable for life in the past?	Definition There are dried-up riverbeds on Mars
Term Some astronomers suggest that, rather than being a planet, Pluto is just a large member of	Definition The Kuiper belt
Term Where did the elements heavier than hydrogen and helium come from?	Definition They were produced inside stars.
Term Why did the solar nebula flatten into a disk?	Definition It flattened as a natural consequence of collisions between particles in the nebula, changing random motions into more orderly ones.
Term Which of the following is the origin of almost all the large moons around the Jovian planets?	Definition They were formed by condensation and accretion in a disk of gas around the planet.
Term Which of the following puzzles in the solar system cannot be explained by a giant impact event?	Definition The orbit of Triton in the opposite direction to Neptune's rotation
Term Approximately how many other planetary systems have been discovered to date?	Definition One hundred
Term The astrometric technique of planet detection works best for	Definition Massive planets around nearby stars