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The Milky Way is the galaxy that are our Solar system to resides in. It is also the very first galaxy that astronomers were aware of. The word galaxy gets its name from the Greek Galaxios which means milky circle. This refers to the band of light that is visible in the night sky. This is the visible portion of the Milky Way galaxy that we can see from Earth. It has been observed by several cultures and though to have many meanings. For example the Mayans thought that the Milky way was a celestial path that lead to the underworld.
The Milky Way Galaxy is a spiral galaxy. This type of galaxy has a center with arms of clustered stars spiraling out. The Milky Way Galaxy is estimated to have anywhere from 200 billion to 400 billion stars. If that does not give you an idea of how big it is, the Milky Way is roughly 100,000 light years in diameter. That basically means if we even had the technology to traverse it at the speed of light it would take hundreds of generations to travel across the Milky Way. Another interesting feature is that the Milky way seems to have a massive black hole at the center that is several times greater than most observed in space.
The Milky Way was considered to be a celestial phenomenon, but few astronomers realized that it was actually composed of distant stars. This was because the ancient astronomers believed the stars where fixed on a celestial sphere that surrounded the Earth. This lead philosophers like Aristotle to believe that the Milky Way was actually the result of the ether between the stars being ignited. However the ancient philosopher Democritus ,the first person to theorize the existence of the atom, made a more accurate guess. He proposed that the Milky Way was actually a cluster of distant stars. This was the first discovery of a galaxy and the hint that the universe was much larger than originally thought. Further observations with improved telescopes helped to confirm these ancient findings. Astronomer Edwin Hubble not only confirmed the existence of the Milky Way but also of other galaxies.
There are still many mysteries about the Milky Way and other galaxies that have not been explained. For instance, the Milky Way and its fellow galaxies are more massive than they appear. Astrophysicists have determined that this means there is a type of matter not observable under any currently known form of radiation. Hopefully future research should reveal more about this unique type of matter.
If you enjoyed this article there are several others on Universe Today that you will enjoy. There is a great article about Edwin Hubble and his discoveries. You can also learn more about Democritus and his work on the atom.
There are also many great resources online that you can use to learn more about the Milky Way. There is a great article about the structure of the Milky Way on the University of California San Diego Astrophysics website. you can also check out the Milky Way page on the University Corporation for Atmospheric Research website.
You can also listen to Astronomy Cast. Episode 99 is about the Milky Way.