1. 星系
    A galaxy is an extremely large group of stars and planets that extends over many billions of light years.

    e.g. Astronomers have discovered a distant galaxy.
           天文学家们发现了一个遥远的星系。

2. 银河；银河系
    The Galaxy is the extremely large group of stars and planets to which the Earth and the Solar System belong.

galaxy的近义词

    e.g. The Galaxy consists of 100 billion stars.
           银河系由1,000亿颗恒星组成。

3. 一群（名人）；（人才）荟萃
    If you talk about a galaxy of people from a particular profession, you mean a group of them who are all famous or important.

    e.g. He is one of a small galaxy of Dutch stars on German television.
           出现在德国电视上的荷兰明星为数不多，他是其中一位。