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Oral Exam 1

# Oral Exam 1 - Oral Exam Questions CH 1 What is the...

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Oral Exam Questions CH. 1 What is the difference between a solar system and a galaxy? A solar system includes the Sun, all the major planets, all their various moons, and asteroids or comets. However, a galaxy is a huge assemblage of stars and universe that contains billions of stars within it. How is an astronomical unit (AU) defined? Give an example of a situation in which this unit of measure would be convenient to use. Astronomical Unit is a unit of length that is used by astronomers to measure distances across the solar system. For example, the average distance between Earth and the Sun is 93 million miles, but it is also equal to 1 AU. What is the advantage to the astronomer of using the light-year as a unit of distance? The light-year is the distance that light travels in one year. This is a useful concept for astronomers because the speed of light in empty space always has the same value (3.00x10 8 m/s). CH. 2 What is the celestial equator? How is it related to the Earth’s equator? How are the north and south celestial poles related to the Earth’s axis of rotation? The celestial equator divides the sky into northern and southern hemispheres, just as the Earth’s equator divides the planet into two hemispheres. The north and south celestial poles are where the Earth’s axis of rotation intersects the celestial sphere. Where on Earth do you have to be in order to see the north celestial pole at the zenith? What is the maximum possible elevation of the Sun above the horizon at that location? On what date can this maximum elevation be observed? If one stands at the North Pole, one can see the north celestial pole at the zenith. The maximum possible elevation of the Sun at the North Pole is 23.5 degrees during Summer solstice (June 21 st ). What are the vernal and autumnal equinoxes? What are the summer and winter solstices? How are these four points related to the ecliptic and the celestial equator? Vernal equinox refers to the Sun passing northward across the celestial equator around March 21 st each year. The autumnal equinox refers to the Sun passing southward across the celestial equator around September 22 nd . Summer solstice is the point on the ecliptic farthest north of the celestial equator, while the winter solstice is when the Sun is farthest south of the celestial equator. Where on Earth do you have to be in order to see the Sun at the zenith? Will it be at the zenith every day? Explain. If one stands at either the autumnal equinox or the vernal equinox where the ecliptic intersects the celestial sphere, one can see the Sun at the zenith directly above. CH. 3 Explain why the Moon exhibits phases. Are they caused by the Earth’s shadow? The Moon exhibits phases because as the Moon orbits around the Earth from one night to the next, we here on Earth see different amounts of the illuminated half of the Moon by the Sun. This common misconception is simply

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false. The phases are the result of our seeing the illuminated half the Moon at different angles as the Moon orbits around the Earth.
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Oral Exam 1 - Oral Exam Questions CH 1 What is the...

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