Astronomy 100

Section 2, Fall 2008

Homework H

Due Wednesday, November 5

On your scantron fill out your NAME, STUDENT NUMBER, and NETWORK ID both in writing and in the bubbles. In addition, fill out "FORM H."

1. We know the temperatures of the planets, Sun, and stars from application of
a) The Wien and Stefan-Boltzmann Laws
b) Newton's laws of temperature
c) Kepler's laws
d) Newton's generalization of Kepler's laws
e) Weber's laws of magnetism

2. We know the chemical composition of the Sun from its
a) spectrum
b) rotation
c) temperature
d) magnetism
e) convection

3. The surface of the Sun is
a) an opaque hydrogen-helium gas
b) solid hydrogen
c) liquid molecular hydrogen
d) liquid metallic hydrogen
e) made of gaseous iron and nickel

4. The temperature of the Sun's corona is about
a) 3500 K
b) 5800 K
c) 2 million K
d) 20 million K
e) 200 million K

5. The third most abundant element in the Sun is
a) hydrogen
b) iron
c) oxygen
d) helium
e) lithium

6. If you took all the hydrogen and helium away from the Sun, the resulting mixture would have a chemical composition rather similar to
a) the Earth's crust
b) a comet
c) Jupiter
d) Saturn
e) Ganymede

7. The Sun rotates
a) every 25 days at the equator in the direction of the planetary orbits
b) once a week in the direction of the planetary orbits
c) every 25 days opposite to the direction of the planetary orbits
d) once a day opposite to the direction of the planetary orbits
e) not at all

8. Sunspots are produced by
a) coronal mass ejections
b) nuclear explosions
c) magnetic fields that block convection
d) the solar wind
e) hurricane like low-pressure areas

9. Absorption lines in the solar spectrum are produced by
a) the electrons associated with atoms and ions
b) the protons associated with atoms and ions
c) the neutrons associated with atoms and ions
d) all of the above
e) none of the above

10. The solar corona is heated by
a) radiation
b) convection
c) conduction
d) magnetism
e) cometary impacts

11. What event on the Sun causes aurorae on Earth?
a) coronal mass ejections
b) thermonuclear explosions
c) sudden sunspot disappearances
d) irregular solar rotation
e) radioactivity

12. The Sun's magnetic field is produced by its
a) corona
b) wind
c) nuclear reactions
d) rotation and convection
e) sunspots

13. The lifetime of a particular sunspot is closest to
a) a minute b) a week c) a year d) 11 years e) 22 years

14. The length of the solar sunspot cycle (ignoring the direction of magnetic fields) is
a) a week b) a year c) 11 years d) 22 years e) 33 years

15. The solar wind
a) is produced by comet tails and flows into the Sun
b) is a flow of particles from the Sun
c) blows into the Sun from the Van Allen radiation belts
d) is a flow of neutrinos from the solar center
e) is the thin gas in interplanetary space falling into the Sun.

16. When the sunspots (magnetic activity) disappeared around the year 1700,
a) the number of northern lights displays increased
b) nothing else happened
c) the Earth's magnetic field disappeared
d) there were no eclipses of the Moon
e) North America and Europe became colder

17. Where does solar hydrogen fusion take place?
a) the photosphere
b) the solar wind
c) the corona
d) sunspots
e) the deep core

18. In the center of the Sun, two protons fuse directly to
a) deuterium
b) helium-3
c) helium-4
d) nothing
e) gamma rays

19. About how much hydrogen-burning time does the Sun have left to it, in billions of years?
a) 1 b) 5 c) 10 d) 50 e) 100

20. What particles immediately escape the solar core following fusion?
a) neutrinos
b) protons
c) gamma ray photons
d) neutrons
e) positrons

21. What makes the Sun hot in its center (hot enough to run fusion)?
a) the strong force
b) gamma rays
c) tides raised by the planets
d) rapid interior rotation
e) gravitational compression

22. Why does the Sun not explode as a hydrogen bomb?
a) It will
b) The last reaction of the proton-proton chain is too fast
c) The first reaction of the proton-proton chain is too slow
d) There is not enough hydrogen left to run the p-p chain
e) We don't know

23. A 2nd magnitude star is how many times brighter than a 12th magnitude star?
a) 10 b) 100 c) 1000 d) 10,000 e) 100,000

24. The absolute magnitude of a star is what the apparent magnitude would be at how many parsecs?
a) 1 b) 10 c) 100 d) 1000 e) 10,000

25. Which magnitude would appear brightest to the naked eye?
a) -1 b) 0 c) 1 d) 10 e) 15