Andromeda galaxy (M31,NGC224) is the biggest spiral in the Local Group. Since it is not far from Galaxy, it provides us a unique candidate that the galaxy structure and morphology can be observed carefully.

• 仙女星系(M31,NGC224)是本星系群中最大的旋涡星系,而且离银河系并不遥远,无疑为我们提供了有利的观测条件。