Why do spiral arms have a blue color?
What will be an ideal response?
Spiral arms are waves of enhanced density of stars and gas in the disk of a galaxy. Stars are widely separated and are not individually affected by the greater crowding in a spiral arm but gas clouds are much larger and, relatively, less widely separated. Thus they suffer more crowding in a spiral arm and the resulting collisions and higher densities are believed to lead to a high rate of new star formation. Any massive stars that are formed will be bluer and brighter than lower mass stars but will live for a much shorter time. Such stars do not have time to diffuse out across the galactic disk and therefore trace the location of the spiral arms, which consequently appear blue.
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Which of the following types of electromagnetic radiation has the lowest energy?
a. x-rays b. visible light c. ultraviolet d. gamma-rays e. infrared radiation
A small source radiates an electromagnetic wave with a single frequency into vacuum, equally in all directions. As the wave moves, its frequency:
1.increases. 2.decreases. 3.stays constant.
In Carol's (and Kaku's) theory of eternal inflation
A) astronomers can never buy much with the money they earn B) our universe undergoes extremely fast expansion forever C) many baby universes form, most of which are dead, but some which are similar to ours D) the universe has 35 different dimensions which we can access through black holes E) the universe continues to expand at a constant rate from the time of the Big Bang until the present
What is unusual about Triton?
A. It orbits its planet backward. B. It does not keep the same face toward its planet. C. It is the only moon with its own rings.