Self Assessment Week 14

Question The scientist who made the first telescopic survey of the Milky Way and discovered that it is composed of a huge number of individual stars was

Galileo Galilei

Question 2 The central region of our Galaxy is not as flat as its main disk of stars. Which of the following has roughly the same shape as our central region of stars?

a peanut

Question 5 Astronomers observe the Small Magellanic Cloud (SMC), a not very dense, rather small galaxy near us. They notice that even those stars that formed recently have relatively few heavier elements (when compared to such recent stars in our Milky Way.) What is the likely explanation for this deficiency?

because the SMC is small and its stars are widely spaced, the rate of star formation (and star death) is much slower there

Question 6 Which of the following was not done by Edwin Hubble?

discovering the relationship between period and luminosity of a cepheid variable

Question 7 Which type of galaxy is very difficult to see, but (astronomers recently realized) may be very common?

dwarf elliptical

Question 10 The new instrument that made it possible for Edwin Hubble to demonstrate the existence of other galaxies in the early 1920's was:

the 100-inch reflector on Mount Wilson

Question 1 William Herschel thought that the Sun and Earth were roughly at the center of the great grouping of stars we call the Milky Way. Today we know this is not the case. What was a key reason that Herschel did not realize our true position in the Milky Way?

the dust that extends throughout the disk of the Galaxy only allowed Herschel to see the small part of the Milky Way that surrounds us

Question 8 Among irregular galaxies, what makes the Large and Small Magellanic Cloud especially useful for astronomers?

they are (for galaxies) very close to us, so they are easy to study

Question 3 How do astronomers measure the mass that the Galaxy contains inside the orbit of the Sun?

they measure the distance to the center of the Galaxy and the period of the Sun's orbit and then use Kepler's Third Law

Question 9 Which of the following is NOT a characteristic of a spiral galaxy?

when we take spectra of its stars, they have far less of the heavier elements than the Sun