Explaining The Universe on Instagram: "The Andromeda Galaxy (M31) is the nearest large spiral galaxy to the Milky Way and lies about 2.5 million light-years from Earth in the constellation Andromeda. It contains roughly one trillion stars, making it larger than our galaxy, and spans about 220,000 light-years across. Andromeda is moving toward the Milky Way at about 110 km/s, and in roughly 4–5 billion years the two galaxies are expected to collide and merge into a single giant elliptical galaxy.