The amount of dark matter in the universe is
A) about the same as the amount of visible matter.
B) many times more than the amount of visible matter.
C) about twice as much as the amount of visible matter.
D) many times less than the amount of visible matter.
E) entirely unknown at the present time.
Question 2
By observing gas clouds orbiting the centers of galaxies, we have learned that galaxies are made mostly of dark matter. In these observations
A) the light from the gas clouds is obscured by some unseen material.
B) the low speeds of the gas clouds show that they are being slowed by some unseen material.
C) the high speeds of the gas clouds show that they are being pushed by some unseen material.
D) the low speeds of the gas clouds show that they are gravitationally attracted to the center by unseen material.
E) the high speeds of the gas clouds show that they are gravitationally attracted to the center by unseen material.
By reflecting most visible light, snow creates a much cooler microclimate than nearby bare ground.
Visible Light Spectrum
Observable Universe
Amount of Energy Released by Earthquakes of Different Magnitudes
Fear of dark
The three states of matter: solid, liquid, and gas.