| Explain whether the galaxy is moving toward or away from Earth and how you know | How many kilometers away would the mirror have to be? Each orbit of Io takes 42 |
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| Earth travels the distance calculated in part a in 42 | Earth travels the distance calculated in part a in 42 |
Galactic Motion How fast is a galaxy moving relative to Earth if a hydrogen spectral line of 486 nm is red-shifted to 491 nm? Each orbit of Io takes 42.
30| Galactic Motion How fast is a galaxy moving relative to Earth if a hydrogen spectral line of 486 nm is red-shifted to 491 nm? Suppose that you wanted to measure the speed of light by putting a mirror on a distant mountain, setting off a camera flash, and measuring the time it takes the flash to reflect off the mirror and return to you, as shown in Figure 16-24 | Suppose that you wanted to measure the speed of light by putting a mirror on a distant mountain, setting off a camera flash, and measuring the time it takes the flash to reflect off the mirror and return to you, as shown in Figure 16-24 |
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| How far does light travel in 13 s? Without instruments, a person can detect a time interval of about 0 | Calculate how fast the galaxy would be moving relative to Earth |
How far does light travel in 13 s? How many kilometers away would the mirror have to be? Calculate how fast the galaxy would be moving relative to Earth.
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