From studies of the rotations of galaxies and dynamics of clusters, we now think that about ________ of the mass of the universe is composed of dark matter
Fill in the blank(s) with correct word
90%
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Mars has a sufficient mass and a low enough temperature that water molecules could exist in its atmosphere as vapor. One reason Mars's atmosphere does not contain a significant amount of water vapor is that
a. Mars formed in a part of the solar nebula that lacked oxygen. b. Mars formed in a part of the solar nebula that lacked hydrogen. c. all of the water vapor was released in the impact that formed Deimos. d. ultraviolet radiation breaks the water molecule into less massive particles that can escape. e. the water molecule combines readily with chlorine to form hydrochloric acid.
The greatest variation in size, mass, and luminosity occurs in
A) globular clusters. B) elliptical galaxies. C) spiral and barred spiral galaxies. D) type I vs type II irregulars. E) Seyfert galaxies.
Emission nebulae occur only near stars that emit large amounts of ________ electromagnetic radiation
A) infrared B) radio C) visible light D) ultraviolet E) X-ray
How is dust usually observed around young protostars in stages 4-6?
What will be an ideal response?