midterm3F08 - ASTRONOMY 100 Dr. Nick Warner 5:00 pm, April...

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1 ASTRONOMY 100 Dr. Nick Warner MIDTERM 3 ____________ 5:00 pm, April 15 th , 2008 SOLUTIONS AT THE END Exam Number Time Allowed: 1 hour _________________________ Name (Please Print) 1. The Oort cloud is a) a band of dust in the plane of the ecliptic, extending from the orbit of Mars to beyond the orbit of Neptune b) an approximate spherical distribution of comets centered on the Sun, extending out to about 50,000 AU c) another name for the early solar nebula d) a relatively flat distribution of comets in the plane of the ecliptic, extending from around the orbit of Neptune out to about 500 AU from the Sun e) the broadest band of asteroids in the asteroid belt, separated from other bands by Kirkwood Gaps 2. It is very likely that the Sun will one day become a a) black hole b) neutron star c) supernova d) red dwarf e) white dwarf 3. Approximately what percentage of observed stars lie on the main sequence a) less than 1% b) about 10% c) about 50% d) about 90% e) more than 99% 4. A piece of space debris that does not burn up completely in the Earth’s atmosphere, and actually hits the ground is called a) a meteorite b) a meteoroid c) a meteor d) an asteroid e) a bludger 5. The idea of a 'standard candle' is important as a means of measuring what? a) color b) brightness c) speed d) distance e) chemical composition 6. A sequence of thermonuclear fusion processes inside massive stars can continue to transform the nuclei of elements such as hydrogen, helium, etc. into heavier nuclei and also generate excess energy, up to a limit beyond which no further energy-producing reactions can occur. The element that is produced when this limit is reached is a) carbon b) uranium c) iron d) silicon e) oxygen 7. Nuclear fusion can take place only at very high temperatures, because a) only then the nuclei are fast enough to overcome their electrostatic repulsion b) only then the nuclear reactions produce energy c) otherwise the nuclei are surrounded by electrons which prevent the direct collision of two nuclei d) otherwise the nuclei disintegrate too fast to be available for fusion
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2 8. From the center outward, the order of the layers or parts of the Sun is a) radiative zone, convection zone, corona, chromosphere, photosphere b) radiative zone, convection zone, chromosphere, photosphere, corona c) corona, chromosphere, convection zone, photosphere, radiative zone d) radiative zone, convection zone, photosphere, chromosphere, corona e) convection zone, radiative zone, chromosphere, photosphere, corona 9. Which of the following gives four of the spectral classes listed in order from reddest and coolest to hottest and bluest a) ABFG b) GFBA c) OFGK d) KAGO e) MGAO 10. To say that a star is in hydrostatic equilibrium means that a) there is a balance between the fuel burnt and the energy released b) there is a balance between the fuel burnt and the change in the gravitational field c) there is a balance between the weight of the upper layers and the pressure in the lower layers
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midterm3F08 - ASTRONOMY 100 Dr. Nick Warner 5:00 pm, April...

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