Astronomy A100 Midterm 1 solutions
Fall 2006
______________________________________ Name
Multiple Choice (3 points each):
1) Is Polaris (aka the North Star) the brightest star in the night sky?
a) yes
b) no
c) it is tied with other stars for the brightest
d) Polaris is not up at night
2) Which of the following best describes the Ecliptic plane?
a) the path the moon covers in the sky
b) the path the sun covers in the sky
c) another term for the celestial equator
d) all of the above
3) In Ptolemy’s model, where was the position of the earth?
a) in the center
b) in orbit around the sun
c) just off of the center
d) Ptolemy’s model did not include the earth
4) The ancient Greeks knew the earth was a sphere.
a) true
b) false
5) Which of the following is the most accurate statement about the views of ancient
Greece?
a) All believed that the earth was the center of the universe.
b) Most that the earth was the center of the universe, but a few argued
that the sun could be at the center.
c) Most that the sun was the center of the universe, but a few argued that the
earth could be at the center.
d) All believed that the sun was the center of the universe.
6) During the time of Ancient Greece and in the early Dark Ages, what was at the
North Celestial Pole?
a) nothing
b) Vega
c) The moon
d) Polaris (aka the North Star)
7) Which of the following most accurately describes Ptolemy’s model for the Solar
System?
a) Earth was near the center, circular orbits, no epicycles
b) Earth was near the center, circular orbits, with epicycles to explain
retrograde motions
c) sun near the center, circular orbits, no epicycles
d) sun was near the center, circular orbits, with epicycles to explain
retrograde motions
8) Which of the following most accurately describes Copernicus’s model for the
Solar System?
a) Earth was near the center, circular orbits, no epicycles
b) Earth was near the center, circular orbits, with epicycles to explain
retrograde motions
c) sun near the center, circular orbits, no epicycles
d) sun was near the center, circular orbits, with epicycles to explain
retrograde motions
9) The telescope was invented by:
a) the Arabs about 900 AD
b) the Vikings about 1200 AD
c) Galileo about 1600 AD
d) Isaac Newton about 1700 AD
10) Which of the following was not an accomplishment of Tycho Brahe?
a) Proving that comets were not in the atmosphere.
b) Created a sun centered model of the solar system which was accepted
by later astronomers (although the public disregarded it during his
lifetime).
c) Made measurements of Mars to an accuracy of 1 arc minute
d) Tycho did all of the above.
11) What is Kepler’s 1st law?
a) orbits are circular
b) orbits are elliptical
c) orbits are triangular
d) orbits have no shape
12) If the sun is at 1 focus of the earth’s orbit, what is at the other focus?
a) the sun
b) the moon
c) nothing
d) the earth
13) What is Kepler’s 2nd law?
a) equal area with equal time
b) the area per time depends on what part of the orbit you are in
c) orbits are not constant, so there is no way to calculate the area per time
covered
d) orbits don’t exist
14) What is Kepler’s 3rd law?
a) orbits are circular
b) the earth is the center of the universe
c) the sun is the center of the universe
d) The square of the period relates to the 3rd power of the semi-major
axis
15) Which of the following does Galileo NOT get credit for?
a) Inventing the telescope.
b) Being the first to observe Neptune.
c) Observing Sunspots.
d) Galileo get credit for all of these
16) Which of the following does Galileo NOT get credit for?
a) finding the mountains on the moon
b) discovering that gravity accelerates all objects at the same rate regardless
of their masses
c) discovering the rotation of the sun
d) Galileo gets credit for all of these things
17) Newton Discovered that as 2 objects get further apart:
a) the force of gravity drops
b) the force of gravity remains constant
c) the force of gravity increases
d) the force of gravity no longer exists once the 2 objects are separated
18) Newton also discovered:
a) That apples fall faster than pears.
b) That gravity only exists on the surface of an object.
c) That gravity extends outward far beyond the earth.
d) That gravity at large distances creates a repulsive force which keeps
everything from crashing into the sun.
19) The corona of the sun is several million degrees. If a spacecraft could shield itself
from the rest of the sun, how would the corona affect the ship?
a) move it forward in time
b) fry it
c) crush it
d) nothing
20) On what part of the sun would you find sun spots?
a) corona
b) core
c) photosphere
d) radiative zone
21) You have a solid object at some temperature. What type of spectrum of light will
it emit?
a) none
b) emission
c) continuous
d) absorption
22) Where on the sun could you land?
a) bottom of the photosphere
b) core
c) coronal hole
d) no where
23) How dense is the sun?
a) about as dense as air
b) about as dense as water
c) about as dense as lead
d) more dense than any material on the earth!
24) In the radiative zone, how long does it take a single light photon to go from the
bottom of the radiative zone to the top of the radiative zone?
a) 10 seconds
b) 10 minutes
c) 10 years
d) 1 million years
25) From which part of the sun is most of the light we can see emitted from?
a) corona
b) core
c) photosphere
d) radiative zone
26) Which is the correct order of the layers of the sun from the center to the furthest
out?
a) core, radiative zone, convection zone, photosphere, corona
b) core, radiative zone, convection zone, corona, photosphere
c) core, convection zone, radiative zone, photosphere, corona
d) core, convection zone, radiative zone, corona, photosphere
27) The spectrum of the sun has absorption lines. What does that tell us about the
sun?
a) What the sun is made of.
b) The top layer of the photosphere is “thin”.
c) The top of the photosphere is cooler than the bottom.
d) All of these.
28) Which of the following is NOT a light wave?
a) an X-ray
b) a radio wave
c) a gamma ray
d) these are all light waves
29) You have a solid object surrounded by a cooler gas. What kind of spectrum will
this produce?
a) none
b) emission
c) continuous
d) absorption
30) You have a “thin” cool gas with nothing behind it. What kind of spectrum will
this produce?
a) none
b) emission
c) continuous
d) absorption
SHORT ANSWER: (15 points each)
1) Name 4 types of objects you can see in the night sky which are astronomical (and
outside our atmosphere).
Planets
Moon
Stars
Constellations
Satellites
Galaxies
2) Why did Ptolemy’s model last for 1400 years? Give at least 2 reasons. 4
sentences maximum.
 It worked! It was accurate!
 400 yrs later the dark ages slowed progress of science to a standstill
 The church tended to control beliefs
 Nobody did measurements accurate enough to be able to show the flaws in the
system.
3) Early in his career, Kepler made a somewhat accurate model of the solar system
using circular orbits. His model agreed well with most of the observations made
by his mentor Tycho Brahe. However, at two places in the orbit of Mars, his
model differed from the observations by 8 arc minutes (which is only ¼ the
diameter of the moon). What did Kepler decide was the cause of this error? How
did Kepler rectify this error (if at all)? How did this decision impact astronomy
(if at all)? 1-2 sentences per question maximum.
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•
•
He decided the model was in error.
He fixed the error by trying different orbits than circular and finally came upon
elliptical orbits.
This created models based on observations, and gave us the solar system as we
understand it to be today.
4) What is a sunspot? If you were directly above a sunspot (so that you could not
see the rest of the sun), would the sunspot appear to be dark or bright, and why? 3
sentences max.
•
•
•
A sunspot is a dark part of the sun which is cooler than the rest of the surrounding
areas.
A sunspot would be bright.
Sunspots just appear dark because they emit a less light than the surrounding
areas.