The largest member of the Local Group is Andromeda, a spiral galaxy like ours. Andromeda is about 2.2 million light-years away and about one and a half times larger than the Milky Way—150,000 light-years across.
With about 300 billion stars, its gravitational pull causes several smaller satellite galaxies to orbit around it. Two of these elliptical satellites can be seen with a small telescope.
The Andromeda galaxy is moving toward the Milky Way at about 186 miles per second. It would take about 2 billion years, but it is possible that the two galaxies could collide or merge into each other.
Like the Milky Way, the spiral galaxy Andromeda revolves around a central “bulge.” Scientists believe this center contains a massive black hole.