Andromeda Galaxy -- The most famous of all galaxies is also the most distant object visible to the naked eye, and the nearest major galaxy to our Milky Way. In some ways its spiral structure resembles that of our own galaxy, but it is about twice as massive. The galaxy is most visible in the northern sky towards the end of autumn and beginning of winter. Andromeda's proximity will be deadly to our galaxy. Astronomers estimate that it will collide with the Milky Way in about 5 billion years.