Question

No astronomical object that produces a continuous visible spectrum of light has ever been observed. However, there are many astronomical objects that produce emission or absorption spectra. Read the following descriptions of astronomical objects, and then sort the labeled images into the appropriate bins according to the type of spectrum each object produces. Drag the appropriate objects to their respective bin.
- Emission nebula: a cloud of hot, interstellar gas glowing as a result of one or more nearby young stars that ionize the gas.
- Planetary nebula: a glowing cloud of hot, low-density gas that is ejected from a red-giant star.
- Sun: a glowing ball of extremely dense gas powered by nuclear fusion in its core, but surrounded by a low-density, cooler atmosphere.
- Atmosphere on Titan: a layer of cool, low-density gas confined close to the surface of Titan, one of Saturn's moons.

Answer 1

Spectroscopy is an extremely valuable method of astronomical study. Astronomers can determine the composition, density, and temperature of celestial objects by interpreting the light that is either emitted or absorbed by the objects.

Emission spectrum
- (image 1) emission nebula
- (image 2) planetary nebula

Absorption spectrum
- (image 3) atmosphere on Titan
- (image 4) Sun