The Milky Way Galaxy is the second largest galaxy, after Andromeda, in the Local Group. This galaxy is currently measured to be 27 trillion times the mass of our sun, which puts it more then ten times the mass of the Milky Way - it is definitely a giant. The Triangulum Galaxy (a.k.a., the Star Wars galaxy) is the third largest. Recently, astronomers were able to take new measurements of a small, faint galaxy near the Milky Way and are now able to say for sure it's the smallest galaxy ever found. The supermassive black hole believed to occupy the center of the Milky Way is closer to Earth than previously thought, according to a revised model of the galaxy. Dwarf Galaxy Pisces A. Astronomers have spotted the smallest "rogue planet" candidate yet known, a Mars- to Earth-mass world that apparently cruises through our Milky Way galaxy unattached to a star. Galaxies can be grouped into three categories based on size: dwarf galaxies, mid-range spiral galaxies, and gigantic elliptical galaxies. Milky Way Galaxy. Galaxies are the building blocks of the universe and have existed for more than 13 billion years. A dwarf galaxy is a small galaxy composed of about 1000 up to several billion stars, as compared to the Milky Way's 200–400 billion stars. Solar System. The Milky Way is a well-known galaxy because it contains Earth and its Solar System. Other globular clusters that orbit the center of our Milky Way as a satellite – i.e. The free-floating planet is between the sizes of Mars and Earth. The nearest of these is the Sagittarius dwarf, a galaxy that is falling into the Milky Way Galaxy, having been captured tidally by the Galaxy’s much stronger gravity. If you know what all of these things are it's pretty obvious which is biggest, Earth is IN the solar system, the solar system is part of the Milky Way, which is part of the local group of galaxies which is part of the Virgo supercluster all of which are in the universe. Additional close companions have been found, all of them small and inconspicuous objects of the dwarf elliptical class. Perhaps 60 other smaller dwarf galaxies abound, and hundreds if not thousands of … Astronomers have detected the smallest rogue planet in our Milky Way galaxy. The core of this galaxy is about 90,000 light-years distant. [+] Andromeda is the biggest, the Milky Way is #2, Triangulum is #3, and the LMC is #4. Earth. As with many things that talk about items on an astronomical scale, this requires a little bit of information to accurately process.