Final answer:
The Sun and the atmosphere on Titan have absorption spectra, while nebulae, such as emission and planetary nebulae, exhibit emission spectra.
Step-by-step explanation:
Objects with an absorption spectrum absorb specific wavelengths of light which are then absent in the spectrum we observe. These dark lines in the spectrum correspond to the energies associated with transitions between energy levels in atoms or molecules.
For the given options:
- Emission nebula – These typically have an emission spectrum rather than an absorption spectrum, because the gas in the nebula is excited by nearby stars and emits light at characteristic wavelengths when electrons drop to lower energy levels.
- Sun – Has an absorption spectrum in its photosphere where elements such as hydrogen, helium, and metals absorb light and create dark lines known as Fraunhofer lines.
- Atmosphere on Titan – Similar to Earth's atmosphere, Titan's atmosphere also has an absorption spectrum, with certain wavelengths absorbed by compounds in the atmosphere.
- Planetary nebula – Like the emission nebula, a planetary nebula exhibits more of an emission spectrum due to the ionized gas radiating specific wavelengths.
In summary, the Sun and the atmosphere on Titan exhibit absorption spectra, while nebulae, including both emission and planetary types, are typically associated with emission spectra.