A dwarf galaxy is "a small galaxy composed of several billion stars, less than the 200-400 billion stars of our Milky Way" (Wikipedia). On February 23, 2014, it was reported that two galaxies that once orbited the Andromeda Galaxy were merging. The collision created a stream of stars in one of Andromeda's dwarf galaxies, Andromeda II. The researchers then observed the stream of stars by separating them into categories and trying to analyze which might be members of Andromeda II versus what might be “dwarf stars in the foreground of the Milky Way halo” (Amorisco et al, 2014, p 4). Because the stream of stars is located in an area of ​​Andromeda II that has limited luminosity, the researchers found 14 “high-probability contaminants” in a region of the stream with “stars that [were] significantly more likely to belong to the population of Andromeda II. ” (Amorisco et al, 2014, p. 4). By measuring the characteristics of the flow, the researchers were able to conclude that it showed "remnants of a merger between two dwarf galaxies... illustrating the scale-free character of galaxy formation, down to the lowest galactic mass scales" (Amorisco et al, 2014, p. 1). As we discussed in the lesson, galaxies are constantly colliding with each other, and these collisions shape the structure and evolution of galaxies. “Andromeda II provides direct evidence of the importance of mergers even for smaller and less luminous galaxies” (Amorisco et al, 2014, p. 3). By discovering more evidence of galactic collisions, cosmologists and astronomers will be able to determine the effect they have on the Universe. The merger of galaxies allows them to grow larger: small galaxies merge to create... the center of the map... is observed between the satellites Andromeda and the Milky Way and is believed to be due to differences in formation and/or evolution of dwarfs” (Martin et al, 2006, p. 1989). This suggests that collisions could have other impacts on the universe depending on how often they occur and the speeds at which they collide. The evolution of new dwarf galaxies is evidence that the universe is shaped by colliding galaxies and that galaxies create large balls/clusters of stars when they collide. Dwarf galaxies will, over time, merge with larger galaxies and this cycle will contribute to the growth of the universe. During this course we learned about the expansion of the universe and it seems that the universe will never stop expanding. There is so much that is yet to be discovered despite the fact that our ideas are evolving.