2. Dark matter (missing matter) is matter

whose presence can be inferred by gravitational effects, but it doesn't give off light or detectable radiation.
which appears dark against a brighter background of stars.
that must be located almost entirely in the large voids between superclusters.
barely visible in dim or dark stars but its gravitational effects are very obvious.

3. Dark matter (missing mass) is theorized to exist in clusters of galaxies to explain

the dimming of light from clusters.
the spinning or rotation of clusters.
how galaxies have stayed together in clusters for billions of years.
the expansion of clusters.

4. Gravitational lensing is thought to be a proof of dark matter's existence because light is bent much more around(see Helps & Hints)

stars than around galaxies.
galaxies than can be accounted for by the number of visible stars in the galaxy.
stars than can be accounted for by the mass of the stars.
spiral galaxies than around elliptical galaxies.

5. The amount of mass in the universe that we can study directly from the radiation it gives off is

90-99% of the total.
90-96% of the total.
about 50% of the total.
1-10% of the total.

6. Some dark matter could be in the form of very distant (see Helps & Hints for lesson 12)

stars and black holes.
stars, nebula, and black holes.
planets, black dwarfs and black holes.
planets and nebula.

7. If neutrinos that are created in the cores of stars are

detected, they could account for most of the dark matter.
found to have a tiny mass, they would be the dominate form of matter in the universe.
detected, they would replace gravitons as the dominate form of matter in the universe.
detected, they, plus axions, could account for all the dark matter.

8. The exact rate of expansion of the universe is very important in helping astronomers determine the

mass of the universe.
size of the universe.
age of the universe.
density of the universe

9. The destiny of the universe is closely associated with

its age.
its density.
its size.
the Einstein constant.

10. An open universe is one

that will eventually collapse.
where scientific study can occur in any and all directions.
where galaxies are free to move in all directions.
that will expand forever.

11. If the universe is closed, it is

shaped like a sphere and gravity will slow, reverse and collapse all matter back to a point.
shaped like a saddle and gravity will slow and stop the expansion of galaxies.
shaped like a saddle and gravity will slow, reverse and collapse all matter back to a point.
also flat and gravity will slow, reverse and collapse all matter back to a point.

12. If the universe is open, it is

spherical in shape and will grow colder, darker as energy is depleted.
saddle shaped and will grow colder, darker as energy is depleted.
saddle shaped and gravity will halt the expansion.
basically flat and gravity will reverse the expansion.

13. Critical density means that

if the universe does not stop expanding in the next ten billion years, it will continue expanding forever.
the strength of gravity (the amount of matter) in the universe is balanced by the expansion energy.
if the universe does not collapse in the next ten billion years, it never will.
the amount of energy in the universe is below a critical amount.

14. If dark matter does not exist, then the universe

cannot be open.
cannot be saddle shaped.
cannot be closed.
will collapse.

Lesson 19 "The Origin of the Solar System"

15. The solar system is thought to have formed from

larger fragments that broke up.
a cloud of gas and dust that collapsed and flattened as it rotated.
a cloud of gas and dust that expanded as it rotated.
the collision of our sun with another object.

16. During the early formation of the solar system, the cloud (solar nebula)

flattens like a pancake with a central bulge that eventually forms Jupiter and the giant planets.
only slightly flattens to produce the sun.
flattens like a pancake with a central bulge that eventually forms the sun.
that first flattens then thickens as planets develop.

17. The disk that forms in the early solar system

becomes "lumpy" due to the accretion of particles.
becomes very hot throughout its length and width.
rapidly falls toward the center to form the sun.
expands continuously due to its rotation.

18. When the sun finally turns on (begins to shine with visible light) it has a strong

solar wind that blows off the atmospheres of Jupiter and Saturn.
photon pressure that blows off the atmospheres of Jupiter and Saturn.
solar wind that evaporates the original inner planets.
solar wind that pushes the gas in the disk outward.

19. As planets and a star form from a cloud and disk of debris,

most of the matter goes into forming the planets.
most of the matter goes into making the star.
the matter is almost equally distributed between planets and the star.
most of the matter is pushed out of the disk by the star's solar wind.

20. According to the telelesson, planets in our solar system can be placed into categories called

terrestrial, protoplanetary, ice dwarfs and gas giants.
silicates, protoplanetary, ice dwarfs and gas giants.
terrestrial, gas giants and ice covered planets.
protoplanetary, gas giants and terrestrial planets.

21. Terrestrial planets have iron cores created by

radioactivity that melts the planet followed by iron objects striking the planet and sinking to the center.
silicate planetesimals that accrete to, and cover an iron object.
gravity compressing heavy elements into iron as the planet accretes.
radioactivity that melts the planet allowing iron to sink and form the core.

22. Differences that we see between the composition of planets are largely due to

differences in composition in the early nebula.
when the planet formed.
the differences in temperature and density of materials from the inner solar nebula to the outer.
differences in the size of the solar nebula.

23. Choose the incorrect statement concerning rocky debris in the solar nebula.

Rocky objects bombarded the early planets.
Much of the record of the early bombardment of the Earth by this debris has been eliminated by erosion.
Much of the record of the early bombardment on some planets is still there.
Most of the record of the early bombardment was erased when all the planets melted.

24. Choose the correct statement.

Inside the "ice line" rocky materials could condense; beyond only iron would form.
Inside the "ice line" mainly rocky materials formed; beyond gases and ices collected.
Inside the "ice line" mainly icy materials formed; beyond gases and ices collected.
Inside the "ice line" mainly icy materials formed; beyond rocky materials, silicates and iron could form.

25. According to current theories:

most single stars should have disks and/or planets around them.
most single stars should have disks and/or Pluto-like objects forming near the "ice line".
most stars should have giant planets inside the "ice line" and terrestrial beyond.
most stars should have giant and terrestrial planets inside the "ice line".

Prepared by: Mike MItchell

Be sure to review your quizzes before taking the test.