Introduction Our star 'The Sun' is one of many billions of others like it that make up the Milky Way. Our Milky Way is in turn, one of many billions of galaxies that make up the physical part of the Universe. UG is not aware of any stars that exist that are not part of or close to a galaxy. Galaxies also include comets, asteroids, nebulas, planets etc. Most galaxies are moving away from us but the famous Andromeda galaxy is moving towards us. No need to panic, it will not happen for millions and millions of years and by that time, the entire human race will have be gone, either dead or on another planet.
What is at the centre of the galaxy? No-one knows for sure, some say it's a super-star, a collection of bright stars or a super-black hole. The centre of the Milky Way is so far away, we've not yet been able to determine what is there as yet. What we do know is that we are in the suburbs of the galaxy. Jan Hendrik Oort calculated that the centre is in the direction of the Sagittarian constellation.
How did the Milky Way got its name? Different religions/regions have different views as to how the galaxy came into creation. The term comes from Roman/Greek mythology where after the birth of Heracles, Hera spilled her breast milk in anger of not being the babys mother. Another variation says that it was spilled when Heracles was caught drinking Hera's milk and was pushed off. The word galaxy derives from the greek word for milk, gala. In the beginning, when they looked up at the stars they saw a cloudy/milky area hence the name.
Galaxy Classification A galaxy may be referred to as a NGC or M number, what are they? Galaxies, Nebulas and Star Clusters were first catalogued by Charles Messier, a French Astronomer. His first catalogue consisted of 45 was published in 1774 then grew to 103 in 1781 then finally 110. Later in 1880, the new General Catalogue was started by J.L.E.Dreyer using observations from Sir William Herschel. It contains nearly 8000 objects. Some objects can have both a M number and a NGC number as well. For example, the Andromeda Galaxy is known as both M31 and NGC224.
Types of Galaxies There are four main types of Galaxies, ( Spiral, Lenticular, Irregular and Elliptical ). There are subtypes as well, for example, clockwise spiral and anti-clockwise. The best way to explain the different types is to show you what they look like. The Andromeda galaxy is . Irregular Galaxies also include Starbust Galaxies and Ring Galaxies, example of the former is below. Irregulars lack any shape or definition that the other types do hence their name. Lenticular are said to be lens like in nature.
A Short List of Galaxies
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