29:50 Stars, Galaxies, and the Universe
First Hour Exam
September 24, 2007
Form A

There are 30 questions. Read through each question and all the answers before choosing. Budget your time. No whining.

Walk with Ursus!

1. During the night, the stars rise in the east and move from east to west. This phenomenon is due to
   (a) the revolution of the Earth about the Sun.
   (b) the motion of the Sun through the nearby stars of the Milky Way.
   (c) a flow of stars through the inner solar system.
   (d) the rotation of the Earth on its axis. *
   (e) precession of the Earth's rotation axis.
2. The time it would take a light ray to cross the diameter of the Earth is
   (a) 2-3 seconds
   (b) 3-4 minutes
   (c) less than 0.1 seconds *
   (d) greater than 10 minutes
   (e) 12 seconds
3. Which of the following statements accurately describes the relation between the Sun and Earth on the day of the summer solstice (June 21)?
   (a) The Earth is closest to the Sun on that day.
   (b) The Earth is most distant from the Sun on that day.
   (c) The Sun is at its maximum brightness during its one year cycle.
   (d) The south pole of the Earth is tilted towards the Sun.
   (e) The north pole of the Earth is tilted towards the Sun. *
4. An observer is at the north pole of the Earth. What fraction of the celestial sphere does he or she see?
   (a) all of the celestial sphere
   (b) half of the celestial sphere *
   (c) a portion which depends on the longitude of the observer
   (d) the celestial sphere is not visible from the north pole
   (e) none of the celestial sphere
5. You look up in the night sky and see the planet Jupiter, the planet Mars, and the Moon very close together. You know that they are located in or close to one of the following. Which is it?
   (a) the ecliptic *
   (b) the celestial equator
   (c) the zenith
   (d) the north celestial pole
   (e) the constellation of Hercules
6. Assume that you are on a planet around another star. The star and planet are similar to the Sun and Earth, respectively, with one exception. That exception is that the obliquity of the ecliptic is $70^{\circ}$ rather than $23.5^{\circ}$. Which of the following statements would be true?
   (a) The length of the year would be nearly three times longer than it is on Earth.
   (b) The ``parade of the constellations'' would be faster than on Earth.
   (c) The Sun would never be seen to set on that planet.
   (d) The length of the day would be 70 hours rather than almost 24 hours.
   (e) Seasonal variations would be more pronounced than on Earth. *
7. The meridian is the astronomical term for
   (a) the line across the sky where the Sun and all the planets are to be found.
   (b) the point on the sky straight overhead.
   (c) an imaginary line on the sky that runs from due north, through the zenith to due south. *
   (d) an imaginary line on the sky from straight east, overhead to straight west.
   (e) the day of the year when day and night are of equal length.
8. Both refractor and reflector telescopes have a component called an ``objective''. The role of the objective is to
   (a) electronically amplify the weak signals from stars
   (b) bring parallel rays together at a point called the focus *
   (c) use electromechanical circuits to precisely determine the direction from which the light comes
   (d) magnify the small image at the focus
   (e) record the image from the telescope on film or electronic camera
9. Yesterday was the autumnal equinox. Which of the following phenomena occurred?
   (a) The Sun rose due east. *
   (b) The Sun rose in the northeast.
   (c) The Sun rose in the southeast.
   (d) The Moon and Sun were in the same constellation.
   (e) The Earth was at the closest point to the Sun in its orbit.
10. Last night, Arcturus set in the northwest. Approximately what was its azimuth at the time it set?
    (a) $35^{\circ}$
    (b) $290^{\circ}$ *
    (c) $120^{\circ}$
    (d) $180^{\circ}$
    (e) $0^{\circ}$
11. What was the altitude angle of Arcturus at the time it set?
    (a) $35^{\circ}$
    (b) $290^{\circ}$
    (c) $120^{\circ}$
    (d) $180^{\circ}$
    (e) $0^{\circ}$ *
12. A telescope which employs a large, parabolic-shaped mirror is called a
    (a) reflector *
    (b) refractor
    (c) binocular
    (d) antenna
    (e) grazing-incidence telescope
13. Let's assume that you go out in space to a distance of 10 parsecs. You look back at the Sun. How bright would it appear to you?
    (a) About a factor of 5 fainter than it now appears
    (b) About as bright as the light from the full moon
    (c) About as bright as the stars Vega and Arcturus
    (d) About as bright as the faintest stars we can see with the naked eye. *
    (e) Far to faint to be seen without a large telescope.
14. The light we see is an example of a general phenomenon called
    (a) Alfvén waves.
    (b) Seismic waves.
    (c) nuclear fusion.
    (d) Bose-Einstein condensation.
    (e) electromagnetic waves. *
15. As a spacecraft like Voyager goes deeper into space, it becomes progressively more difficult to communicate with it. Why is this so?
    (a) The length of time from transmission to reception becomes longer and longer, and eventually becomes lost.
    (b) The signal gets absorbed by material in space.
    (c) The position of the spacecraft is not known precisely enough to tell us where to look for it.
    (d) The signal from the spacecraft becomes weaker due to the inverse square law. *
    (e) Computers on the spacecraft lose track of the time to look for the signal from Earth.
16. Imagine that you are looking at the sky on a dark, clear night. Without knowing anything else about them, other than the fact that they are objects like the Sun, what observation could you use to tell whether they are all exactly like the Sun or not.
    (a) They have different colors. *
    (b) Some are bright, and some are faint.
    (c) They can be seen in different parts of the sky.
    (d) Some of them twinkle, while others do not.
    (e) Some stars move from east to west during the night, while others stay stationary.
17. Consider a Jovian planet. At what time will it be closest to the Earth?
    (a) At conjunction, when the planet is in the direction of the Sun
    (b) At opposition, when the angle between the Sun and the planet is $180^{\circ}$. *
    (c) When the planet is on the meridian at sunset
    (d) When the planet is at an azimuth of 120 degrees at sunrise.
    (e) When the planet is on the meridian at sunrise
18. Imagine looking at a globular star cluster like M13 in a large telescope, or at a picture of it taken with a large telescope. You can see many of the stars in M13. Without additional information or measurements, what properties of these stars could you determine?
    (a) their absolute magnitudes
    (b) not the absolute magnitudes, but differences in the absolute magnitudes *
    (c) the spectral types of the stars
    (d) the distances
    (e) the ages of the stars
19. In the Celestial Coordinate System (system fixed with respect to the stars) the two coordinates are
    (a) Right Ascension and Declination *
    (b) latitude and longitude
    (c) galactic latitude and longitude
    (d) altitude and range
    (e) altitude and azimuth
20. A solid, opaque object can be heated to different temperatures. What happens to the light emitted by this object as the temperature increases?
    (a) The spectrum changes from a continuous spectrum to an emission line spectrum
    (b) The object becomes bluer, and stays at the same brightness.
    (c) The power radiated in infrared radiation increasingly dominates that emitted at ultraviolet wavelengths.
    (d) The object gets brighter and the light shifts to shorter wavelengths. *
    (e) The object gets brighter and the light shifts to longer wavelengths.
21. The apparent magnitude is a familiar astronomical quantity which was introduced in class. An equivalent quantity (one which measures the same property) used in physics, and the units used to express it, is
    (a) energy (Joules)
    (b) distance (meters)
    (c) magnetic field (Tesla)
    (d) luminosity (Watts)
    (e) flux (Watts/square meter) *
22. The absolute magnitude is a familiar astronomical quantity which was introduced in class. An equivalent quantity (one which measures the same property) used in physics, and the units used to express it, is
    (a) energy (Joules)
    (b) distance (meters)
    (c) magnetic field (Tesla)
    (d) luminosity (Watts) *
    (e) flux (Watts/square meter)
23. You measure or estimate the apparent magnitude of a star. What piece of information do you need to determine its absolute magnitude?
    (a) distance *
    (b) spectral type
    (c) space velocity
    (d) age
    (e) constellation in which it is located
24. The Voyager spacecraft is presently 105 astronomical units from the Earth. It was launched in 1977. If it keeps going at this rate, approximately how long will it take to reach a nearby star?
    (a) 50 -100 years
    (b) 1 - 3 thousand years
    (c) 100,000 years *
    (d) 50 million years
    (e) 7 - 10 billion years
25. If you go outside in the early evening now (8-9 PM), where will you find Jupiter?
    (a) Low in the southwestern sky *
    (b) Low in the northwestern sky
    (c) Straight overhead, in the vicinity of the zenith
    (d) In the early evening, Jupiter has not yet risen
    (e) In the early evening, Jupiter has already set
26. The average distance between the Sun and the Earth is defined as the
    (a) kilometer
    (b) parsec
    (c) astronomical unit *
    (d) light year
    (e) Solar Distance Unit
27. In the horizon system of coordinates for describing the position of an object in the sky, the two coordinates are
    (a) Right Ascension and Declination
    (b) latitude and longitude
    (c) galactic latitude and longitude
    (d) altitude and range
    (e) altitude and azimuth *
28. Which of the following are (both) units used in expressing stellar distances.
    (a) parsec and astronomical unit
    (b) astronomical unit and light year
    (c) parsec and light year *
    (d) astronomical unit and Gauss
    (e) light year and Tesla
29. At different times of the year we see different constellations in the evening sky. What property of the Earth and Solar System is responsible for this phenomenon?
    (a) the rotation of the Earth on its axis
    (b) the fact that all the planets orbit the Sun in nearly the same plane
    (c) the orbital motion of the Earth around the Sun *
    (d) the Solar System is moving rapidly through space so we see different stars at different times
    (e) it takes the Sun one year to complete an orbit around the Earth.
30. Which celestial object has been prominent in the early evening sky, straight overhead (at the zenith)?
    (a) the planet Mars
    (b) the planet Venus
    (c) the star Antares
    (d) the Andromeda galaxy
    (e) the star Vega *