A Tale of Many Islands: The Andromeda Galaxy
The Andromeda Galaxy (Messier 31) with other galaxies M32 and M110 The Andromeda Galaxy is a fantastic marvel in the night sky right now. It is physically 50% larger than our own galaxy and contains an estimated 300 billion stars. By pairing its large size with a relatively short distance to our galaxy (2.5 million light years), its full appearance in the sky spans that of 6 full moons. However, the portion that is visible to the human eye will appear smaller since only the galactic core is bright enough for us to distinguish. The estimated trajectory of M31 suggests an eventual collision with our Milky Way Galaxy in about four billion years. The Universe as a Solitary Island The earliest recorded observations of the Andromeda Galaxy were written in the year 964 CE by the Persian astronomer Abd al-Rahman al-Sufi in the Book of Fixed Stars . In this book the