1
ASTR 101 Chapter 18 Questions with Correct
Answers | Updated (100% Correct Answers)
Use the words at the left to complete the sentences at right
correctly. You may use the same word(s) more than once. Answer: -
Evidence suggests that two-thirds of the total mass plus energy in
the universe consists of DARK ENERGY.
- We say use the term DARK ENERGY as a name for whatever is
causing the expansion of the universe to accelerate with time.
-The bending of light by gravity is called GRAVITATIONAL LENSING.
-Astronomers suspect that DARK MATTER consists of weakly
interacting massive particles, or WIMPs.
-Matter that emits no light of any kind is called DARK MATTER.
-Large-scale structure in the universe has probably been shaped
primarily by the gravity of DARK MATTER.
-Stars and gas clouds are considered to be forms of LUMINOUS
MATTER.
-Matter that emits X-rays but not visible light is considered a form
of LUMINOUS MATTER.
© 2025 All rights reserved
, 2
Which of the following describes key evidence for dark matter in
individual spiral galaxies like the Milky Way? Answer: Orbital speeds
of stars stay relatively high even at great distances from the galactic
center.
Which of the following provide evidence for dark matter in clusters
of galaxies? Select all that apply. Answer: -The temperature of hot,
X-ray emitting gas within clusters.
-Orbital speeds of galaxies within clusters.
-The way clusters bend light from galaxies behind them.
Consider the portion of the video that shows two galaxy clusters
that have collided, and includes a map showing the inferred
distribution of dark matter among these clusters. How did
astronomers infer the location of the dark matter? Answer: By
carefully observing how the light of galaxies beyond these clusters
has been bent by the clusters.
Why does the rotation curve of a spiral galaxy increase with
increasing distance near the galaxy's center? Answer: The encircled
mass increases so fast that gravity increases with radius.
What is the evidence that there is dark matter beyond the disk of a
spiral galaxy? Answer: The stellar mass distribution does not
account for the rotation curve of galaxies.
© 2025 All rights reserved
ASTR 101 Chapter 18 Questions with Correct
Answers | Updated (100% Correct Answers)
Use the words at the left to complete the sentences at right
correctly. You may use the same word(s) more than once. Answer: -
Evidence suggests that two-thirds of the total mass plus energy in
the universe consists of DARK ENERGY.
- We say use the term DARK ENERGY as a name for whatever is
causing the expansion of the universe to accelerate with time.
-The bending of light by gravity is called GRAVITATIONAL LENSING.
-Astronomers suspect that DARK MATTER consists of weakly
interacting massive particles, or WIMPs.
-Matter that emits no light of any kind is called DARK MATTER.
-Large-scale structure in the universe has probably been shaped
primarily by the gravity of DARK MATTER.
-Stars and gas clouds are considered to be forms of LUMINOUS
MATTER.
-Matter that emits X-rays but not visible light is considered a form
of LUMINOUS MATTER.
© 2025 All rights reserved
, 2
Which of the following describes key evidence for dark matter in
individual spiral galaxies like the Milky Way? Answer: Orbital speeds
of stars stay relatively high even at great distances from the galactic
center.
Which of the following provide evidence for dark matter in clusters
of galaxies? Select all that apply. Answer: -The temperature of hot,
X-ray emitting gas within clusters.
-Orbital speeds of galaxies within clusters.
-The way clusters bend light from galaxies behind them.
Consider the portion of the video that shows two galaxy clusters
that have collided, and includes a map showing the inferred
distribution of dark matter among these clusters. How did
astronomers infer the location of the dark matter? Answer: By
carefully observing how the light of galaxies beyond these clusters
has been bent by the clusters.
Why does the rotation curve of a spiral galaxy increase with
increasing distance near the galaxy's center? Answer: The encircled
mass increases so fast that gravity increases with radius.
What is the evidence that there is dark matter beyond the disk of a
spiral galaxy? Answer: The stellar mass distribution does not
account for the rotation curve of galaxies.
© 2025 All rights reserved
