The Milky Way does not travel through the universe alone. It is accompanied on its journey by smaller galaxies. The two largest are the Small Magellanic Cloud and the Large Magellanic Cloud, which are both visible as dusty twin smudges in the southern hemisphere. When the Magellanic Clouds started orbiting the Milky Way billions of years ago (astronomers are not certain about the timing and the gravitational bond, it’s possible that they are still on their first approach to the Milky Way), an enormous stream of gas known as the Magellanic Stream was ripped out of them. The stream…