8. which of the following statements regarding the moon is correct?
a. the moon's surface doesn't have any craters.
b. the moon's surface exhibits active volcanism.
c. the moon is tidally locked to earth.
d. the moon's surface exhibits plate tectonic activity.

9. which physical law states that all orbits are conic sections?
a. newton's laws
b. kepler's first law
c. kepler's third law
d. kepler's second and third laws

10. in a star, nuclear fusion occurs in the
a. radiative zone.
b. photosphere.
c. corona.
d. core.

11. what's the inner core of the jovian planets made of?
a. helium gas, hydrogen gas, and rocks
b. metals, helium gas, and hydrogen gas
c. bacteria fossils, hydrogen compounds, and ice crystals
d. hydrogen compounds, solid rock, and metals

12. what's the critical error seen in the geocentric model of the solar system exhibited here?
a. the moon is positioned too close to earth
b. the sun is on the wrong sid of earth
c. the sun is positioned to revolve around earth
d. the sun is revolving in the wrong direction

13. what are the two lengths that all ellipses have (all planets)?
a. x and y axes
b. horizontal and vertical length
c. minor and major axes
d. conic and isoconic length

14. which scientist developed the heliocentric model for the solar system?
a. copernicus
b. johannes kepler
c. aristotle
d. ptolemy

15. look at the figure above. which position of the earth represents a solstice?
a. beginning of winter
b. beginning of autumn
c. beginning of spring
d. beginning of summer

16. why do the terrestrial planets lack hydrogen and helium in their atmospheres?
a. hydrogen and helium were converted to other compounds as the planets formed.
b. hydrogen and helium are present in rings around the terrestrial planets.
c. hydrogen and helium were blown away by solar wind.
d. hydrogen and helium can't be retained because the planet masses are too small.

17. which of the terrestrial planets is the largest?
a. earth
b. mars
c. venus
d. mercury

18. what must you know to solve kepler's third law, the law of periods?
a. period of the orbit
b. period of the minor axis
c. period of the major axis
d. period of the revolution around the sun

19. what does einstein's theory of relativity explain?
a. how gravity interacts with planets
b. how light interacts with moisture
c. how light interacts with gravity
d. how magnetism reverses the fields of the poles

20. which of the following lists the correct requirements for a black hole to form?
a. the star must be 10 to 28 times larger than earth's sun, and a supernova explosion must have occurred.
b. the star must be 29 times larger than earth's sun, and a supernova explosion must not have occurred.
c. the star must be 29 times larger than earth's sun, and a supernova explosion must have occurred.
d. the star must be 10 to 28 times larger than earth's sun, and a supernova explosion must not have occurred.