In dictionaries:
Extragalactic astronomy
the branch of astronomy concerned with objects outside the Milky Way galaxy.
extragalactic nebula
Galaxies beyond the Milky Way.
extragalactic background light
All the accumulated radiation in the universe due to star formation processes, plus a contribution from active galactic nuclei (AGNs).
Extragalactic planet
An extragalactic planet, also known as an extragalactic exoplanet or an extroplanet, is a star-bound planet or rogue planet located outside of the Milky Way Galaxy.
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