Answer: large collection of stars, gas and dust held together by gravity.
Explanation:
A galaxy billions of stars, dust and gases. These are held together by gravity.
A galaxy comprises sites of new star formation in nebulae and old star clusters. It has globular clusters as well as loose, dis-organised open clusters.
Usually at the center of each galaxy, there is a super massive black-hole about which all the material in the galaxy rotates about.Galaxies have mainly three types of shapes- spiral, elliptical and irregular.
