The Exam will cover material presented in the lectures and covered in the on-line lecture notes (topic 1-3). Much of the material is also to be found in the lab manual : Sections 1.4, 1.5, 1.6, 2.2; Appendices A, B, and C. The only part of Topic 3 we have not covered is Right Ascension, Siderial Time and Hour Angle (Declination will be on the exam).
The Exam will be true/false, multiple choice and short answer format. After the summary, you will find some sample questions to give you an idea of what to expect.
Here is a list of the major themes we have discussed in class, presented partly in question form. This should give you some idea of the range and scope of the topics.
A. What were some of the historical motivations for interest in astronomy? What kind of objects does one see in the night sky.
B. Know how to use angles on the sky --- both large ones (eg 90 degrees separates the zenith from the horizon; the sun and full moon are 180 degrees apart) as well as small ones (eg the size of the moon is 30 arcmins; the separation of a double star is 10 arcsec). Know the "handy angles".
C. Know the magnitude system used by astronomers to indicate the brightness of stars. Know that a magnitude difference of 5 corresponds to a factor of 100 in brightness, with the smaller (more negative) magnitude for the brighter object. An alternative expression for the link between difference in magnitudes and radio of brightness is that 1 magnitude corresponds to a factor 2.51 in brightness. Know that the magnitude of the star Vega is defined to be zero.
D. Constellations : physical vs cultural significance. What arguments help us identify the cultural origin for the "ancient" constellations. How are modern constellation boundaries defined. Destinguish between constellation and asterism. Over what period of time do constellations change due to stellar motions ? Know the various ways stars are named.
E. Know the basic properties of light : its speed, its wave-like electromagnetic nature. Be able to put in sequence the various wavelength bands of electromagnetic radiation (gamma, X-, ultra-violet, optical, infra-red, microwave, radio) as well as the colors of optical light. Know that the approximate wavelength of light is 400nm (blue) to 700nm (red). Which electromagnetic wavebands can be observed from the ground and which must be observed from space ?
F. Understand the common scientific abbreviations : milli- micro- nano- kilo- mega- giga- .
G. Understand how an image is formed by both a lens and a concave mirror. Understand the meaning of the terms : focal length; focal ratio; primary; secondary; eyepiece; field of view; magnification; angular resolution.
H. Know how to calculate the magifying power of a telescope from the focal length of the primary (or objective) and the focal length of the eyepiece.
I. Know how the light gathering power of a telescope depends on the diameter of the primary.
J. What determines the sharpness of a telescopic image? How does the atmosphere play a role in this, and how much does the telescope limit the sharpness and why?
K. Know how binoculars are labelled --- ie that, for example, 7x50 says their magnification is 7 and the diameter of each objective lens is 50mm.
L. Know the basic designs of refracting, reflecting and Schmidt telescopes. Know the advantages and disadvantages of each type. Why does the Schmidt telescope need the correcting element at the front ?
M. Know the various focus positions that are commonly in use in reflecting telescopes : eg prime, newtonian, cassegrain.
N. Know the two basic types of telescope mounting systems : the Alt-Az mount and the Equatorial mount. Know the advantages and disadvantages of each.
O. Understand the concept of the Celestial Sphere. Know the meaning of the celestial poles and the celestial equator.
P. Understand diurnal motion --- which direction does the earth rotate; how do the stars appear to move in the sky during a 24 hour period ?
Q. Know the observer's view of the sky : the horizon (tangent plane to the earth); the cardinal directions (N,S,E,W); the zenith; nadir; meridian. Know where to find the celestial poles and equator on the night sky. Know that the altitude of the celestial pole is equal to the latitude of the observer. Know what the circumpolar zones are.
R. Know how to label directions at any part of the sky : north takes you to the NCP; West is the direction the diurnal motion takes you.
S. Know what the ecliptic is and why it is inclined relative to the celestial equator by 23.5 degrees. Know that the constellations through which the ecliptic passes are the "zodiac" constellations. Know how the position of the sun on the ecliptic gives rise to the seasons. Understand how, at different times of the year, the suns daily arc across the sky is different, as is the length of the day and night. Understand the terms : equinox and solstice. Know how to calculate the noon altitude of the sun at different times of the year. Understand the terms Arctic and Antarctic circle and Tropics of Capricorn and Cancer. What is special about these latitudes on the earth.
S. Understand the Declination coordinate of a star -- how it is identical to the concept of latitude on the earth, with positive values 0 - 90 from the celestial equator northwards, and negative values 0 to -90 going south. Be able to find the altitude of a star as it transits given its declination.
1. If the size of the box of the lyre of the constellation Lyra is 5 degrees on a side, how many full moons would fit along the side ? How many Suns ?
2. How many arcseconds make up 360 degrees ?
3. If you hold your arm out and make a fist, how many degrees of the sky does it blot out.
4. (T/F) The Dipper is just another name for the constellation Ursa Major.
P>5. In what constellation is the star Sirius? Polaris? Capella?6. Which is brighter, a first magnitude star or a third magnitude star?
7. One star appears 10,000 times brighter than another. What is the difference in magnitudes between these two stars.
8. (T/F) Gamma rays have a longer wavelength than X-rays.
9. Name three wavebands which cannot pass through the earth's atmosphere to reach the ground.
10. What does the prefix "nano" mean ?
11. Sketch the optical layout of our Meade Schmidt-Cassegrain telescopes.
12. For a given telescope, the longer the focal length of the eyepiece, the (smaller,larger) the magnification and the (smaller,larger) the field of view.
13. What is the effective focal length of a telescope with a 4 meter mirror if you observe at the f/8 Cassegrain focus. What focal length eyepiece is needed to yield a magnification of x100.
14. If the faintest stars you can see with an 8 inch telescope are magnitude 14, what is the magnituce of the faintest stars you can see with a 16 inch telescope.
15. (T/F) The zodiac is the group of constellations located within about 9 degrees of the celestial equator.
16. (T/F) The point directly overhead is called the north celestial pole.
17. Briefly state what the following are : Meridian; Zenith; Horizon Plane; Transit; Synodic vs Sidereal period.
18. At what latitude does the noon sun pass directly overhead at mid-summer. What is the special name for this latitude.
19. At about what time of night would you expect to see the constellation Sagittarius rise over the Eastern horizon on May 15 ?
20. Which of the following is a circumpolar constellation ? a) Aquila; b) Delphinus; c) Cassiopeia; d) Canis Major; e) Aries.
21. From what location on the Earth are all parts of the celestial sphere visible for at least some time during the year ?
22. What is the suns location on 21 March and in which direction is it moving with respect to the celestial equator.
23. On what day of the year is the declination of the sun the largest ? What is its value on that day ?
24. Answer the following questions using the fact that Charlottesville is at a latitude of +38 degrees. (You should draw a sketch to remind yourself of the relationship between the various quantities involved.)
Do the 24 questions, write down your choice of answers, then check yourself with these Answers and think about the ones you missed.