Units to cover before the 2nd exam:

1. Units to cover before the 2nd exam: Units: 55, 57, 58: HR diagram

2. Our Sun will eventually A. Become white dwarf B. Explode as a supernova C. Become a protostar D. Become a black hole

3. The spectral type of a star is most directly related to its Absolute magnitude b. Surface temperature c. Size or radius d. Luminocity

4. Which two vital parameters are used to describe the systematics of a group of stars in the HR diagram? • a. Mass and weight • b. Luminocity and radius • c. Surface temperature and mass • d. Luminocity and surface temperature

5. Which of the following astronomical systems are held together by gravity • a. The Sun • b. The Solar System • c. The Milky Way • d. All of them

6. If a new planet were found with a period of revolution of 6 years, what would be its average distance from the Sun? • a. About 1AU • b. About 3.3 AU • c. About 6 AU • d. About 36 AU

7. In order of increasing wavelength the electro-magnetic spectrum is • a. gamma rays, blue light, red light, radio waves; • b. ultraviolet, gamma rays, blue light, radio waves; • c. red light, radio waves, X rays, blue light; • d. visible, ultraviolet, X-rays, radio

8. Light has properties • a. of waves; • b. of particles; • c. none of the above; • d. both a. and b.

9. What is the Law of Inertia? • A body at rest stays at rest unless acted on by an outside force • b. F=ma • c. P^2=A^3 • d. Fg=mMG/R^2

10. Saturn is 9.5AU from the sun and orbits the sun every 29.46 years. What is Saturn’s approximate orbital velocity? • a. 9.5 AU/year • b. 0.1 AU/year • c. 2 AU/year • d. 100 AU/year

11. Convert 742 km to millimeters • a. 7.42 x10^8 • b. 7.42 x10^5 • c. 74.2 x10^8 • d. 7.42 x10^6

12. If the Earth’s axis were tilted by 35 degrees, where would the Antarctic circle lie? • a. 78 degrees S • b. 55 degrees S • c. 78 degrees N • d. 55 degrees N

13. What is retrograde motion? • a. “backward moving”/ or interrupted movement of a planet on the sky • b. Clockwise rotation of the moon around the earth • c. Rotation of planets around the sun • d. Large elliptical movements of comets

14. Which is one of Kepler’s laws: • a. For every action has an equal and opposite reaction • b. Planets move in elliptical orbits • c. F=ma • d. Planets move in perfect circles around the sun

15. A solar exlipse can occur ONLY when • a. the Moon comes between the Earth and the Sun • b. the Sun comes between the Moon and the Earth • c. the Earth comes between the Moon and the Sun • d. the Sun, Moon and Earth form a precise right-angled triangle

16. When dropped by an astronaut on the Moon, two objects of different mass will • a. Have different accelerations proportional to their masses • b. Have different accelerations, the more massive object having the smaller acceleration • c. Have the same acceleration • d. Have no acceleration at all in the airless space

17. According to Newton's laws, a force must be acting whenever • a. an object's position changes • b. the direction of an object's motion changes • c. time passes • d. an object moves with non-zero speed

18. Kepler's first law states that a planet moves around the Sun • a. in a circle with the Sun at the center • b. in an elliptical orbit, with the Sun at the center of the ellipse • c. in an elliptical orbit, with the Earth at the center of the ellipse • d. in an elliptical orbit, with the Sun at one focus

19. If an object has an orbit around the Sun that has an essentricity of 0.1, then the orbit is • a. a straight line • b. exactly circular • c. almost circular, but not quite • d. a long, thin ellipse

20. Why was adaptive optics developed? • a. To compensate for chromatic aberration • b. To prevent distortion of mirrors by the vacuum of space • c. To compensate for the image distortion caused by the Earth atmosphere • d. To prevent fractures of the main mirror.

21. The PRIMARY reason for spreading many radio telescopes across a large area and combining the signals at a central station (i.e. combining radio telescopes to form an interferometer) is • a. to produce a much sharper images of radio sources • b. to avoid interference between signals from separate telescopes • c. to be able to send a more powerful signal to space • d. ensure that cloudy weather only affects a few of telescopes, leaving the others to continue observing

22. The main absorber in the atmosphere for infrared radiation, which impedes observations of astronomical infrared objects, is • a. electrons in the Earth's atmosphere • b. dust in the Earth atmosphere • c. oxygen and nitrogen, the major constituents of the atmosphere • d. water vapor

23. Pieces of metal are heated by varying amount in a flame. The hottest of these will be the one that shows which color most prominently? • a. blue • b. yellow • c. red • d. black

24. To a physicist a blackbody is defined as an object which • a. absorbs all radiation which falls upon it • b. always appears to be black, whatever its temperature • c. always emits the same spectrum of light, whatever its temperature • d. reflects all radiation which falls upon it, never heating up and always appearing black.

25. The specific colors of light emitted by an atom in a hot, thin gas are caused by • a. protons jumping from level to level • b. an electron dropping into the nucleus, producing small nuclear changes • c. electrons jumping to lower energy levels, losing energy as they do so • d. the vibrations of the nucleus

26. When electromagnetic radiation is Doppler-shifted by motion of the source away from the detector • a. the measured wavelength is longer than the emitted wavelength • b. the measured frequency of the radiation remains the same, but its wavelength is shortened, compared to the emitted radiation • c. the speed of the radiation is less than the emitted speed • d. the measured frequency is higher than the emitted frequency.

27. What causes sunspots? • a. differential rotation on the Sun creates vortices, or eddies, which are cooler and darker than the rest of the solar surface • b. solar flares cause the photoshere to expand and cool in the vicinity of the flare • c. magnetic fields breaking through the photosphere inhibit heat conduction where the field is strong • d. masses of heavy elements occlude solar light

28. To what do the words "hydrostatic equilibrium" in the Sun refer? • a. The balance of gravity inward and gas pressure outward. • b. The balance of gas pressure inward and heat outward. • c. the balance of gas pressure outward and magnetic forces inward. • d. the creation of one helium nucleus for the "destruction" of every four helium nuclei.

29. The time taken for neutrinos generated in the thermonuclear reactions at the center of the Sun to escape from its surface is • a. about 1 million years • b. about 100,000 years • c. instantaneous, since neutrinos travel faster than the speed of light • d. very short, around few seconds

30. What problems have observers of solar neutrino run into? • a. The neutrino are of the wrong type (mostly muon neutrinos and no electron neutrinos) • b. The neutrinos are about twice as energetic on average than is predicted by theoretical models of the Sun. • c. Only about 1/3 of the expected number of neutrinos is observed, compared to theoretical models of the Sun. • d. About six times as many neutrinos are observed than expected from theoretical models of the Sun.

31. Spectral types (e.g. O, B, A, F, G, K, M) define uniquely their • a. surface temperatures • b. luminosities • c. sizes of radii • d. brightnesses