Let’s talk about something big, galaxies. Those fantastic and fascinating gigantic objects in deep space. A galaxy is a huge group of stars, some kind of a “metropol” of stars. Even though they seem stable and stationary, they actually develop and move all the time, as all the objects in space. Galaxies are created by the gravitational force, which brings pieces into bigger groups during a long time. Think about our solar system. It is a group of planets orbiting a star. A number of similar solar systems exist in our galaxy, The Milky Way. Our neighboring galaxy, Andromeda, has similar solar systems with its own planets and objects orbiting bigger objects such as stars. These kind of galaxies we have billions in the universe. To make it even more confusing, all those galaxies belong into even bigger system, groups of galaxies. Those groups of galaxies, massive “metropols of metropols” also orbit in the universe. Is this big enough?

Sometimes galaxies and groups of galaxies collide, creating new merged galaxies. This is actually one way for galaxies to “grow”. There are varies sizes of galaxies, from those massive galaxies consisting of 3000 billions of stars to smaller galaxies consisting “only” 200 000 stars. In our galaxy there are around 100-200 billions of stars. There are three types of galaxies, namely elliptic, spiral and irregular galaxies. Elliptic galaxies are the biggest ones. Our own galaxy, the Milky Way, is a spiral galaxy. The irregular galaxies are usually the smallest ones. Scientists claim that elliptic galaxies are born from the collision of two spiral galaxies.

More about galaxies in Wikipedia.

Credit:Hubble Space Telescope/NASA/ESA.