The orbits of population I stars I. are confined to disk of the galaxy. II. are very elliptical. III. are nearly circular. IV. are randomly inclined to the disk of the galaxy.
a. I
b. IV
c. I & IV
d. II & IV
e. I & III
Question 2
Opacity is
a. the balance between the pressure and force of gravity inside a star.
b. the force that binds protons and neutrons together to form a nucleus.
c. the force that binds an electron to the nucleus in an atom.
d. a measure of the resistance to the flow of radiation (photons) through a gas.
e. the temperature and density at which a gas will undergo thermonuclear fusion.
The "Emu in the sky," a constellation defined by dark clouds rather than the stars.
Population Interactions and Communities
A Starburst Galaxy
World Population Growth, 1750-2150
Disk of Enheduanna
World Population, 10,000 B.C. to A.D. 2010