This is what the Andromeda Galaxy would look like were it as bright as the moon. The Andromeda is actually two galaxies that collided 4.5 billion years ago, when the Earth was just forming. It is moving towards us at 200 miles a second. It has a diameter of 220,000 light years and contains more than a trillion stars. That number will grow when a similar collision occurs between Andromeda and our Milky Way in 3-4 billion years. Gravity always wins in the end.