Through the Sloan Digital Sky Survey project, astronomers are studying space with great precision. For the moment, they have studied a fifth of what can be seen and have found eight galaxies turning around the Milky Way. They are tiny galaxies, formed by a maximum of one hundred thousand stars (the Milky Way itself has about one hundred billion stars). In a galaxy found, called Leo T, there is enough gas to form many stars. In others no. Astronomers do not know why they are different.