Formation of the Milky Way
Just like everything in the Universe, our very own Milky Way galaxy has not always been there. About a billion years after the big bang the Milky Way began its formation. At this time in the Universe stars were forming in clusters of gas and stayed in a close community. These clusters of stars were attracted to each other from gravity and eventually merged together to create tiny galaxies. These tiny galaxies were also attracted to each other and would merge with one and another until eventually after billions of years of merging, massive galaxies, like the Milky Way, were formed. Even today the Milky Way is still absorbing smaller galaxies all the time and it is even sometimes given the name the “cannibal” galaxy (Wethington, 2009).
The Supermassive Black Hole
In the center of all galaxies there is a dark and mysterious object, a supermassive black hole. These massive black holes hold the galaxies together, while slowly destroying them from the inside. Black holes are extremely dense objects with a very strong gravitational pull on anything near it, even light. It is unknown what these cosmic monsters are made of or the physics behind them. It is also not known exactly how these supermassive black holes are created, but there are some theories. One theory is that smaller black holes left behind from the deaths of massive stars, much bigger than the Sun, are pulled together to make one massive black hole. The Milky Way's supermassive black hole is called Sagittarius A* (Supermassive black hole, n.d.).
|
Merging with the Andromeda Galaxy
In about 4 billion years from now, our galaxy will collide head on with our neighboring galaxy, the Andromeda galaxy. As reported by Nadia Drake, from National Geographic, "Andromeda and the Milky Way are about 2.5 million light-years apart. Fueled by gravity, the two galaxies are hurtling toward one another at 402,000 kilometers per hour." Once the two galaxies collide they will dance around with each other for about a billion years until they finally settle and create an even bigger galaxy (see video below). Earth, along with the Solar System, will most likely survive this collision (Drake, 2014).
Death of the Milky Way
In around tens of quadrillions of years from now, all the stars in the galaxy will have ran out of fuel and died. The galaxy will be a dark wasteland of remnants of stars and planets. Gravity will still be in effect and do something odd with everything in the galaxy called violent relaxation. This is where two objects of different masses pass by each other and exchange gravitational pulls. According to an astrophysicist named Ethan Siegel, "The lower-mass objects get kicked out of the galaxy, while the higher-mass objects sink towards the center, losing velocity." Eventually after enough time, all that will remain in the galaxy is the higher-mass objects closely rotating around the supermassive black hole. The black hole will devour all the objects remaining, leaving one extremely massive black hole. After somewhere between 10^80 and 10^100 years, this will also be dead due to a phenomenon known as Hawking radiation, which will slowly decay the black hole until it is ceases to exist. At this point our galaxy will be dead (Siegel, 2017).
|