[COSMIC BODIES] – When Galaxies Collide

16 Sep

Collisions within the Universe are essential for its continued existence. Mass explosions and impacts will endure to take place like they have done for over 13 Billion years since the Universe’s birth. Asteroids, moons, planets and even stars all go through this process of death and re-birth via impacts, but what about whole clusters of stars? Even galaxies some 200 million light years across are also victim to this force of nature. What are the consequences and what has this got to do with us?

Our galaxy the Milky Way sits across the sky as a smokey band of stars and nebulae. From the Southern Hemisphere you can see this band stream elegantly above the horizon. Obviously it is difficult for ourselves to see our galaxy side on, so we take from examples of similar galaxies of size and characteristics. We live within what is known as a ‘barrel spiral galaxy’ consisting of up to 400 billion stars, some 120,000 light years across. Beauty is usually followed by complexity in the cosmos and nothing seems more complex than a system of this many stars heading straight for one another.

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Two such systems that are currently entangled together are NGC 4038 and NGC 4039 or ‘Antennae Galaxies’ part of the NGC 4038 collection of galaxies.  Currently this system appears like a heart in the sky, seeming to be interlocked at the centre, sending the outer stars spiraling in tails across the cosmos. This phenomenon started to occur some 700 million years ago and is scheduled to continue for at least the next 400 million. As they continue in this mesmerizing cosmic dance, stars will career past each other at over 650,000 mph. A hurtling mass of stars, moons, planets and cloud will stream past each other narrowly missing while chaotically disrupting the laws of physics.

Magnetic fields will be thrown upside down and around and round, climates will be thrown into turmoil as atmospheres are ripped from the surfaces of moons and planets. This vision of hell is hard enough to compromise let alone imagine. The chances of life surviving while under this gravitational entanglement seems unlikely and most certainly impossible when you consider the ‘Stephan’s Quintet’ collective or ‘Pandora’s Cluster’.

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Named after it’s discoverer Edouard Stephan in 1877, ‘Stephan’s Quintet’ is a major galaxy cluster which features 4 out of 5 close galaxies combining into quite a spectacular tango of stars. Found within the Pegasus constellation these four galaxies span a distance of 340 Million light years at nearly the same distance from Earth. Pandora’s Cluster (Abell 2744) is a very similar in quantity to Stephan’s, as in the combination of galaxies but they are somewhat different. Pandora’s bunch seems to be at a rather different stage. There are more gases present around the cluster suggesting that friction and gravity have super-heated the space around the collision and somewhat spread out the destruction. Stephan’s Quintet and Pandora’s Cluster are marvelous examples of the sheer power and force the Universe has to offer. The force that goes into these types of collisions has the same amount of energy as the expulsion of more than 100 Million Supernovae. Unbelievable.

Positives to take away from these cataclysmic events are that in actual fact collisions are extremely rare between the stars and planets that populate these regions. It is hard to believe that an event of this size and quantity of objects, that nothing hits one another. Well it is that fact of size again. Infrequent collisions indicate that the distances between each star are still to great to affect each other. However, being in the middle of one of these events is not good news and our planet, like millions of others it is on course for a cosmic tango with death.

Our galaxy ‘The Milky Way’ is heading straight for our neighboring spiral galaxy, ‘Andromeda’ at over 310,000 mph with no brakes. Both galaxies tails will interlock first twisting into one another as the force of gravity builds and builds between all the smaller masses inside. Planets will start to spin and distort with the force pushed upon them by an invisible nature. Magnetic fields protecting any sort of biospheres or atmosphere will be torn from their surfaces. Unsettled centrifugal forces will reverse orbits, disrupt cores and tear apart worlds. Stars will heat up and expand outwards away to the external reaches of their solar systems engulfing everything in the already uninhabitable heat.

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For the moment we are safe, from Andromeda at least, this collision isn’t scheduled to take place for at least another 4 Billion years, more than a quarter of the existence of the entire Universe.

Regardless of the small chances of stars colliding it is still a reality. This is sill however not the end of the world (providing no planets are involved). Collisions of this power and energy will eventually settle into new nebulae creating hundreds if not thousands of new stars.

Collisions of this magnitude breads life and death into the cosmos. Where there is catastrophe in clashes there is creation within the remnants.

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