Astronomy Chapter 1 Answers – Flashcards
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constellations
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a human grouping of stars in the night sky into a recognizable pattern
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celestial sphere
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a canopy of stars resembling as astronomical painting on a heavenly ceiling
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The star Polaris
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better known as the Pole Star or North Star
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celestial poles
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the points where Earth's axis intersects the celestial sphere are called the north and south
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celestial equator
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midway between the celestial poles lies the equator representing the intersection of Earth's equatorial plane with celestial sphere
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Day to day changes
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the stars position in the sky do not repeat themselves exactly from one night to the next
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sidereal day
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the time needed between successive risings of a given star
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solar day
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the period of time between the instant when the sun is directly overhead (noon) to the next time it is directly overhead
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sidereal month
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time required for the moon to complete one trip around the celestial sphere
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sidereal year
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is slightly longer than the tropical year, and the constellations migrate around the calendar over the course of thousands of years
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Earth moves in two ways simultaneously:
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1. rotates on its axis 2. while at the same time revolving around the sun Each time Earth turns once on its axis, it also moves a small distance along its orbit about the Sun. Earth, therefore, has to rotate through slightly more than 360 degrees for the Sun to return to the same apparent location.
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ecliptic
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because of Earth's orbital motion, the Sun appears to move relative to the background stars over the course of the year, tracing out a path on the celestial sphere
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summer solstice
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The points on Earth's orbit here our planet's North Pole comes closest to pointing in the direction of the sun or equivalently, where the sun is at its northernmost point above the celestial equator (June 21)
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winter solstice
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Six months later, the North Pole points farthest from the Sun or the Sun is at its southernmost point below the celestial equator (December 21)
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seasons
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The tilt of Earth's rotation axis relative to the ecliptic causes
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The universe
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Which of the following can be described as the totality of all space, time, matter, and energy?
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Vanished Stars
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Most of the chemical elements that make up our bodies come from
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Which of the choices below correctly lists things in order from largest to smallest?
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Universe, Milky Way, Solar System, Sun, Earth
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True
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The distances to bodies in the solar system are a few light minutes to light hours.
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A "light-year" is a unit used for what kind of measurement?
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Distance
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A few thousands (2000-3000)
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About how many stars are visible on a clear, dark night with the unaided eye alone?
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88
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Into how many constellations is the celestial sphere divided?
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North Pole
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Where on Earth would you be if Polaris were directly overhead?
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True
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Only at the equator are all the stars visible over the course of the year.
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True
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Over the course of a night, Polaris moves less than any other visible star in the sky.
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year
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the time it takes for Earth to complete an orbit around the Sun
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North Pole
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Where would you be if the Sun sets for six continuous months, beginning about September 23rd?
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Ecliptic
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What celestial line is a product of the Earth's orbit around the Sun?
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Vernal and autumnal equinoxes
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Night and day have approximately equal length at what time or times of the year Earth's axis of rotation is perpendicular to the line joining Earth to the Sun, so day and night are of equal length
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Spring equinox
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The Sun rises due east today, but will rise slightly north of due east tomorrow
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summer solstice
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longest day (most daylight) of the year the noontime Sun reaches its highest point of the year
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fall equinox
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the Sun had declination 0 degrees today, but will have a negative declination tomorrow
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winter solstice
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The sun crosses the meridian 23.5 degrees lower in altitude than the celestial equator the noontime Sun casts the longest shadows sunset occurs at its farthest point south of due west for the year
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first quarter moon
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it is the half moon of the evening sky it is the highest in the sky at sunset it rises about noon it occurs about a week after new moon
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Why aren't there lunar and solar eclipses every month?
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The Moon's orbit is inclined 5 degrees to the ecliptic.
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Why is a synodic month (the time needed to complete one cycle of lunar phases) longer than a sidereal month (the time taken by the Moon to complete one orbit around Earth) and not shorter?
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Because Earth is moving in its orbit around the Sun in the same angular direction while the Moon orbits Earth
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Which of the following types of eclipses will NEVER be observed?
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An annular lunar eclipse
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A solar eclipse can only happen during a
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new moon
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A lunar eclipse can only happen during a
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full moon
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If you are in the Moon's umbral shadow, then you will witness
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a total solar eclipse
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What conditions are necessary for a total solar eclipse?
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new moon on ecliptic near perigee
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True
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At apogee, the Moon is at its farthest from the Earth and thus appears larger than normal. Because of this, it can produce total solar eclipses, but not annular solar eclipses.
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annular eclipse
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A solar eclipse that occurs when the new moon is too far from Earth to completely cover the Sun can be either a partial solar eclipse
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total lunar eclipse
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Anyone looking from the night side of Earth can, in principle
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penumbra
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During some lunar eclipses, the Moon's appearance changes only slightly, because it passes only through the part of Earth's shadow
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total solar eclipse
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can occur only when the Moon is new and has an angular size larger than the Sun in the sky.
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umbra
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A partial lunar eclipse begins when the Moon first touches Earth's
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node
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A point at which the Moon crosses Earth's orbital plane
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Modern scientific theories are
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elegant, testable, simple, and continuously tested
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An effective theory
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must be continuously tested
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a defining characteristic of scientific theories?
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must be continually tested should be as simple as possible to explain the facts they must be testable through experimental verification
