3.When astronomers measure the mass of the galaxy Triangulum using the Brightness Method the result
they get is much less than when they measure the mass using the Orbital Method. This fact can best be
explained by the fact that
a) the stars in Triangulum are made of lighter elements than those in the Sun.
b) the Orbital Method underestimates the mass of Triangulum.
c) Triangulum contains a large amount of unseen mass.
d) Triangulum contains only mass that emits visible light.
4. Observations that indicate the presence of dark matter have been made in
a) only the Andromeda and Triangulum galaxies.
b) only the Andromeda, Triangulum, and Milky Way galaxies.
c) every galaxy that has been examined for dark matter.
d) many, but not all, galaxies that have been examined for dark matter.
5. Evidence for dark matter comes from observations of
a) the orbit of the Moon around Earth and gravitational lensing.
b) the orbits of stars and gravitational lensing.
c) the orbit of the Moon around Earth and the orbits of stars.
d) the orbits of stars, the orbit of the Moon around Earth, and gravitational lensing.
6. Dark matter is called "dark" because it
a) only emits high-energy radiation such as X-rays and gamma rays.
b) only emits low-energy radiation such as microwaves and radio waves.
c) reflects light but does not emit other radiation like stars do.
d) does not emit or reflect any type of radiation or light.
7. Most physicists think that most dark matter is made of
a) WIMPs or axions.
b) brown dwarf stars.
c) black holes or planets.
d) stars like the Sun.
8. Which of the following is true?
a) Physicists know exactly what dark matter is made of.
b) Physicists have no idea what dark matter is made of.
c) Only some physicists know what dark matter is made of.
d) Physicists have some ideas about dark matter, which they are currently testing by experiments.
