Question

simulation courtesy of astronomy education at the university of nebraska - lincoln (https://astro.unl.edu). note: you can access a full - screen version of this tool here.
part (a)
when the telescope is pointed at the incandescent light bulb, which type of spectrum is displayed in the spectrometer? continuous correct select part
part (b)
when the telescope is pointed at the incandescent light bulb with the gas cloud between the two, which type of spectrum is displayed in the spectrometer? absorption correct
part (c)
when the telescope is pointed at the gas cloud from above, which type of spectrum is displayed in the spectrometer? emission correct
part (d)
if the gas cloud re - emits the light it absorbs, why does the spectroscopic view of the bulb seen through the gas cloud show an absorption spectrum rather than a continuous spectrum (in which any absorption lines would have been “filled” again by the re - emitted light)?
the light is re - emitted in random directions, rather than strictly in the direction it was originally traveling.
the light is, in fact, re - emitted in the same direction it was originally traveling, but slowly so that it always appears there is still some light missing.
the light is re - emitted back toward the bulb, recharging its brightness.
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Explanation:

When gas cloud absorbs light from bulb, it re - emits light in random directions. So, not all the absorbed light returns to the original path towards the telescope. This causes the observed spectrum to still show absorption lines instead of a continuous spectrum as the re - emitted light doesn't "fill" the absorption lines in the direction of the telescope.

Answer:

The light is re - emitted in random directions, rather than strictly in the direction it was originally traveling.