They use a spectrograph so the answer would be B.
A parsec is a measurement of distance.
Answer:2 ft/s
Explanation:
Given
Length of Pole is 9 ft
Length of Joe is 3 ft
Joe walks away from Pole at the rate 4 ft/s
Let Joe is x m away from Pole so its shadow length is x'
From Similar triangle concept
3x'=x+x'
x=2x'
and it is given 
Differentiating
Answer:
The correct answer is option C. Sun.
Explanation:
The tail of a comet as well as the comma are visible thanks to the influence of sunlight on these objects.
If there is a case that these objects cross the inner Solar System,<u> then they will be visible from Earth</u>. The reason why this occurs is that as the comet approaches the internal solar system, the materials that are inside the comet vaporize and flow out of the nucleus thanks to solar radiation, and while they do carry dust with them.
This dust is the one that reflects sunlight directly, while the <u>gases shine because of ionization.
</u>
Usually we will need a telescope to see a comet, although there are some that can be seen with the naked eye.
Explanation:
They will repel, meaning that they are made of an electrical conductor.
