Before Edward Hubble people always thought that Milky Way and the Universe are the same thing. Hubble proposed that they are many galaxies. Charles Messier produced a catalouge in which he wrote his observation. However little did he know that many of his observations were actualy galaxies. Such as M31 was later found to be the galaxy Andromeda.
At one second the universe was an atom. Microseconds later it became what it is today. In the first few miutes when the temperatures were above trillion trillion degrees celsius chemical reactions within atoms caused the first elements to be formed, hydrogen andhelium to be formed. These elements were soon found in large chunks known as stars. Due to gravity stars started to be found in clusters known as galaxies.
Galaxies started to move away from each other in the ever expanding universe. Galaxies are fighting between the battle of forces in which gravity is trying to collide galaxies and the universe is trying to spread out galaxies.
DiscoveryIn Ancient tomes people thought that the Earth was in the centre of the Universe and all other bodies relove around it. Only objects in the solar system that could be een by naked eye were believed to exist. Copernicus who opposed this model propesed his own model in which the sun was in the centre of the solar system and its gravititation held planets in its orbit. With the invention of the telescope varius astronomers disovered varius celestial bodies outside the solar system. However it was Edward Hubble who proposed that the Universe contains trilllions of galaxies and the solar system was part of the galaxy, the Milky Way. Thus modef Astonomy and Cosmology was born.
Scientests today have identified thousands of galaxies accros the Local Supercluster and beyond.
There is a long debate between cosmologists about the future of galaxies and the universe. Many think that oat one point gravity will merge galaxies together and bring the universe into what it was earlier: The size of an atom. However many also think that gravity will never be able to stop the Universe form expanding and the Universe will last for ever!
- DK Encyclopedia of Space.