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x-rays don't reach the surface of Earth
X-ray telescopes are located in orbit around the Earth because
An observer will measure the wavelength of waves eminating from a source that is moving away as longer than it really is.
bluer than it is
If a light source is approaching you at a speed very close to the speed of light, it will appear
Star B must be bigger
Star A and Star B have the same temperature, but star B is more luminous than star A. What can you infer about these two stars?
As they move thru space, the vibrating electrical and magnetic fields of a light wave must move perpendicular to each other.
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