noun
Milky Way galaxy; the Galaxy
Specifically refers to our own galaxy, the Milky Way. In astronomy, it is the proper name for the galaxy that contains our solar system.
銀河系には数千億の恒星がある。
There are hundreds of billions of stars in the Milky Way galaxy.
銀
A supermassive black hole is thought to exist at the center of the Milky Way.
noun
galactic system; galaxy
A broader astronomical term for any galaxy or galactic system. Less common than 銀河 (ぎんが) for general 'galaxy'.
アンドロメダ銀河系は、我々の銀河系に最も近い大きな銀河系の一つだ。
The Andromeda Galaxy is one of the nearest large galaxies to our Milky Way.