NAME _____________________________ ID # ____________ LAB # ________
Astronomy 1001 Dr. Thomas W. Jones
Midterm #1 Fall 2000
Read Instructions Carefully:
The short answer questions of this exam are graded by more than one person, so it is imperative that your NAME BE LEGIBLY WRITTEN ON EACH PAGE OF THE ESSAY PORTION!
1. MARK THE ANSWERS YOU CHOOSE ON THIS TEST AS IT IS YOUR ONLY
OPPORTUNITY TO CHECK WHICH ANSWERS YOU GOT RIGHT OR
WRONG. This will not be done for you at a later time in the departmental office.
Exams will be returned to the alphabetical boxes in the North wall of the Physics
building approximately 3-4 days after the exam.
2. Print your NAME, ID # and SECTION # on your answer sheet where appropriate. Your
SECTION # should read 03. All three items are necessary for the proper scoring and
computer transfer of your scores.
3. Use a pencil, make your marks dark and neat, and erase thoroughly.
4. There is only one answer to each question. Choose the best answer.
5. You may use this test for scratch paper.
6. One page (two sides) of notes is allowed for the exam.
I. Multiple Choice (2 pts. each)
1. Which of these is evidence that some meteorites were once parts of much larger bodies?
a) they sometimes contain large, metallic crystals that required very slow cooling
b) the inclination of their orbits varies somewhat
c) an overabundance of gold which is characteristic of large objects
d) the presence of water which would evaporate in interplanetary space
e) radioactive dating
2. The main cause of the slowing down of the rotation of Earth is
a) the periodic appearance of comets
b) tidal friction due mainly to the Moon
c) the occasional bombardment of cosmic rays
d) inaccuracies in even the best clocks
e) none of these; Earth is actually speeding up
3. There are a number of very large impact craters on the surface of the Moon, but few on the Earth. This difference is because
a) the moon has no atmosphere to burn up the meteors before impact
b) the Earth's stronger gravity deflects most meteors towards the moon
c) the Earth's crust is softer, allowing the crater to sink back to flat with
d) the Earth is covered with oceans
e) the Earth has weather and an active crust
4. The acceleration of gravity on the surface of Earth
a) is greater for more massive objects
b) does not depend on the mass of falling object
c) is the same as that on the moon
d) depends on the object's volume
e) is impossible to measure according the the equivalence principle
5. The Moon rises at 6 p.m. Roughly what will be the clock time of the next official moonrise after that, at the same location?
a) 6 p.m. b) midnight c) 7 p.m. d) noon e) 5 p.m.
6. Earth's atmosphere has a larger fraction of oxygen molecules than is found in other planets' atmospheres in the Solar System. Why?
a) biological activity on Earth maintains a high concentration of oxygen gas
b) ultraviolet light from the Sun creates ozone in the upper atmosphere, which chemically breaks down to form oxygen
c) when the Solar System formed, chemical composition depended on distance from the Sun, and Earth is in the oxygen-rich zone
d) water on Earth's surface helped draw oxygen from the rocky crust, but the other planets don't have liquid surface water
e) oxygen is held by the Earth’s magnetic field
7. The atmospheres of Jupiter and Saturn are composed mainly of
a) hydrocarbons
b) methane and ammonia
c) nitrogen and water vapor
d) hydrogen and helium
e) carbon dioxide
8. On the summer solstice in June, the earth's north pole
a) points perpendicular to the ecliptic plane
b) is tipped slightly toward the Sun
c) points almost straight toward the Sun
d) points 90 degrees away from the sun
e) is pointed slightly away from the Sun
9. The meteor showers observed at certain times during the year are believed to be due to
a) minor planets
b) debris left along the path of a comet
c) asteroids
d) pieces of the moon
e) material left over from the formation of Earth
10. The mass of Jupiter is about ____ the mass of the sun.
a) 1/2 b) 1/30 c) 1/100 d) 1/1000 e) 1/300000
11. The Atlantic Ocean seems to have widened as the continents moved apart. What caused this?
a) mineral crystals grow at the bottom of the sea over geological ages, forcing the sea to grow wider
b) the ocean widened soon after the Earth was formed, because of many impacts by meteoroids that existed in the early Solar System
c) tidal forces exerted by the Moon slowly pull the continents apart
d) the Moon originated 4 billion years ago where the Pacific Ocean is found today; its formation stretched the crustal layers
e) convective currents in the mantle cause new rock to move upward under the sea, so the floating continental plates drift apart
12. If you did not know how long a year is, which of these would be a practical and accurate method of estimating the length of the year? (Suppose that this must be done within a limited time, say before three years have passed.)
a) Observe which constellation the Moon is in when it is full, count the months and days before it returns to the same place
b) Keep track of seasonal events (day of first snowfall, for instance) and count the days between recurrence
c) Observe the precise angular size of the Sun, in order to determine when Earth is a perihelion
e) Keep track of the apparent positions of Mars or Venus with reference to the ecliptic
a) Note the time when a star rises as seen from a selected location, count the days until it rises again at the same solar time
13. The four planets closest to the Sun are composed primarily of
a) hydrogen and helium
b) carbon, oxygen and nitrogen
c) methane and ammonia
d) rock and iron
e) dirty ice
14. According to Newton's laws of motion, if an astronaut freely floating in space were to push on a nearby spacecraft,
a) it would not move but the astronaut would move away
b) both would move in the direction of the push
c) the spacecraft, being more massive, would accelerate much more than the astronaut
d) spacecraft and astronaut would inevitably start spinning
e) it would move away and the astronaut would recoil from it
15. The light-gathering power of a telescope is related directly to
a) the focal length of its primary mirror or lens
b) the ratio of focal lengths of its primary and secondary mirrors or lenses
c) the image quality of its optics (resolution)
d) the area of its primary mirror or lens
e) whether it uses a primary lens or a mirror
16. On the average, the whole Earth is about twice as dense as the rocks of the crust. What is the explanation?
a) Earth is of uniform composition throughout, but high pressure makes the central core denser
b) the centrifugal force of rotation reduces the density in the outer layers
c) the tidal effects of the Sun and Moon increase the central density while also reducing the crustal density
d) continental drift induces cracks and cavities in the outer layers
e) Earth has a massive core of dense nickel and iron, which is further compressed by high pressure
17. The most damaging blow to Earth-centered theories of the universe came from the
a) discovery of sunspots
b) fact that bodies of different weight, fall at the same rate
c) discovery that the moon orbits Earth
d) discovery of Jupiter's moons and phases of Venus
e) doppler shifts of stars
18. Which of these are observed on the surface of Mars?
a) giant volcanoes b) polar caps c) dry river beds d) all of a-c e) none of a-c
19. In Ptolemy's theory, planets moved in circles which also moved in circles. This complicated structure seemed necessary to explain
a) retrograde motion of planets
b) that planets stay close to the ecliptic
c) why planets vary in brightness from month to month
d) why sidereal time is different from solar time
e) the seasons
20. According to Kepler's 2nd Law, a planet moves fastest in its orbit when it is
a) approaching the Sun
b) receding from the Sun
c) farthest from the Sun
d) nearest to the Sun
e) in retrograde motion
NAME _____________________________ ID # ____________ LAB # ________
Astronomy 1001 Dr. Thomas W. Jones
Midterm #1 Fall 2000
II. Short Answers (2 pts. each) (State your answers in 1-3 complete sentences.)
1) In ancient times one argument against motion of the earth around the sun was an absence in those days of observed parallaxes among the positions of stars. The earth does orbit the sun, so how do we today reconcile these two facts?
2) Larger bodies in the solar system, such as the major planets, are very nearly spherical, whereas smaller ones are irregular in form. Why?
3) Carbon dioxide gas constitutes less than 1% of the earth’s atmosphere, yet it is very important to determining the surface temperature of the earth. Why?
NAME _____________________________ ID # ____________ LAB # ________
Astronomy 1001 Dr. Thomas W. Jones
Midterm #1 Fall 2000
4) List three key properties of the solar system that must be explained in any successful scientific theory of its formation. One property should relate to the motions of the planets, one to their elemental compositions, and one to how matter is distributed among small and large objects.
5) The sizes of impact craters on the earth or moon are much larger than the sizes of the objects that made them. Why and what determines the sizes of the craters?