Our galaxy: the Milky Way

The Milky Way was formed approximately 13 600 millions of years ago, with a marge of error of approximately 800 millions of years. At the same time of the formation of the Milky Way, the solar system, and 200 000 millions and 300 000 millions of stars more. However, there are people that think that there are about 400 000 millions of stars. This gives to our galaxy bigger dimensions than normal, in fact, there are many other galaxies that have a lot less stars than ours. The Milky Way has an approximately diameter of 100 000 light years, this means that it would last 100 000 years at the light velocity, which is of 300 000 km/s, and exactly, of 299 792, 458 km/s, to go to the other side of the Milky Way.

The galaxies in the universe are classified in different types depending of their visual morphology, what means, depending of their appearance. The Milky Way is a spiral galaxy. This type of galaxies are the most known and they are characterised because of their spiral arms in which are situated the stars that form them. In this case, the solar system is situated in the Orion arm, one of the four arms that has the Milky Way. Our system is situated in the galaxy’s surroundings, far away from the supermassive black hole of the galaxy’s centre (like in many others), that we think that for the moment is asleep because he doesn’t swallow material. But this isn’t the only type of galaxy in the universe, there are elliptic, lenticular and irregular galaxies.

Our galaxy forms part of a group of them which we’ve called Local Group. This group of galaxies contains 33 of them, of which our galaxy is the biggest of them after Andromeda, one of the galaxies closer of us. Unfortunately, our galaxy and the nearby one (Andromeda) go with a collision trajectory the one with the other, but, fortunately, we don’t have to worry about anything for the moment, actually, the two galaxies will fuse in about 4 000 million years. Further than the Local Group, there are cumulus of galaxies where there can be a lot more galaxies than in the Local Group, hundreds more. There are even more galaxies in the supercumulus, this can be home of thousands of them. To have an idea, the nearest supercumulus to us is the supercumulus of Virgo, this is small of them, but even if it’s likes this, it has about 2 000 galaxies.

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