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Astronomy 100

Chapter 2-The Sky

The Greek-letter designation indicates a star's relative brightness and constellation
In the constellation Orion, we receive more light from the star Rigel than we do from the star Betelguese. Why does this figure have the alpha and beta designations as shown? This is one exception to the way in which brightness has been assigned in this system
Which statement below most accurately describes modern constellations? They are 88 well-defined regions on the celestial sphere
The precession of Earth's rotational axis causes the location of the all of the above
The apparent visual magnitudes of four stars are listed below. Of these four stars, which one appears dimmest in the sky? +2.8
At what location on Earth is an observer if the celestial equator passes through the point directly overhead? At Earth's equator
The bowl of the Big Dipper is about 10 degrees wide. Use this figure to determine the angular separation between Polaris and the upper pointer star of the Big Dipper. About 30 degrees
If Earth's rotational period changed to 16 hours, and Earth's shape remained the same, how would this affect Earth's precession? The precession cycle would be longer than it is now
Which of the following is an asterism? the Big Dipper
If the apparent visual magnitude of the sun is -26.5 and that of the full moon is -12.5, what is the approximate light-intensity ratio of sunlight to full moonlight received on Earth? About 400,000
On a clear, very dark night far from city lights, how many stars are visible to the naked human eye? A few thousand
How many apparent brightness classes did Hipparchus assign to stars? 6
If the tilt of Earth's axis were to change from 23.5 degrees to 0 degrees, what celestial circles would coincide for all observers? The celestial equator and the ecliptic
At what location on Earth is an observer who has the south celestial pole directly overhead? At Earth's South Pole
From which of the following countries is the north celestial pole never above the horizon? Australia
What is the faintest apparent magnitude that can be detected by the human eye on a clear, very dark night? 6
The apparent visual magnitude of star A is 2 and the apparent visual magnitude of star B is 1. Based on this information, which statement below must be true? Light output and distance cannot be determined from a star's apparent visual magnitude alone
You observe that the north celestial pole is 42 degrees above the horizon. What does this information tell you? That your latitude is 42 degrees north
Which pair of apparent visual magnitudes listed below indicates that we receive about 16 times as much visible light from star W as we do from star X? m star W = 2, and m star X = 5
When you observe a star on the celestial equator over a period of a few hours, you notice that it moves from east to west relative to the horizon
The remaining 48 ancient constellations that we still recognize today are located at mid and northern celestial latitudes
From what location on Earth are all constellations circumpolar? Both North and South Poles
What is responsible for the motion described in the previous question? Earth's rotation on its axis
What is the most likely Greek-letter name of the second brightest star in the constellation Lyra? beta Lyrae
Use this figure to determine which constellation will be the nearest to the north point on the horizon 15 hours into the future. Perseus
From what location on Earth are no constellations circumpolar? The equator
Why does Earth's rotational axis precess? The sun and moon pull on Earth's equatorial bulge
If Earth's equatorial bulge was larger and more massive, and Earth's rotation rate remained the same, how would this affect Earth's precession? The precession cycle would be shorter than it is now
In this figure it is apparent that the radius of the precession circle is 23.5 degrees. At what latitude on Earth is the entire precession path currently above the horizon? At all locations north of 23.5 degrees north latitude
Notice in this figure that the magnitude scale is "awkward" in that the smaller, or more negative, magnitude number corresponds to a brighter star. Why does the scale have this "awkward" direction? The system was originally set up as a set of classes with first class as the brightest
Created by: dabruns