Our Milky Way Galaxy might seem all big at strong at first, but are we really safe in this spiralling gorgeousness? While our Solar System will remain habitable for at least a few billion years more with Sun burning brightly to keep planet Earth all warm and cosy, the Milky Way is on a dreadful collision path with another galaxy, and it won’t end good. But will it be a devastating experience or do we stand a chance to see the birth of a completely new galaxy? That is, of course, if humanity lasts long enough to observe this cosmic event.
It’s not the first time
It seems that galaxy clashes aren’t that rare judging by the state of our very own Milky Way. Astronomers made some findings in 2018 that suggest Milky Way devoured a dwarf galaxy back in the day. It wasn’t big – not bigger than the Small Magellanic Cloud – but it is a disturbing fact nonetheless. The galaxy’s name was Gaia-Enceladus and now there’s almost nothing left of it apart from a cluster of gorgeous blue stars inside the halo of Milky Way.
It’s all part of the stellar evolution
Believe it or not, but without this catastrophic collision our galaxy simply wouldn’t look the way it does today. The exploration of the Gaia-Enceladus incident allowed scientists to pinpoint almost the exact time when the clash happened – some 10 billion years ago. So there were two galaxies back in the day: one was massive and packed with metals, while the other, Gaia Enceladus, was much lighter and smaller in size. The collision was quite appalling, creating chaos within two galaxies, ending with complete demolition of Gaia-Enceladus. This event kick-started star-forming processes, which continued for billions of years. As a result our Milky Way galaxy was born!
Milky Way is a hungry galaxy
Our Milky Way has been munching on dwarf galaxies all throughout its history, adding them to its spectacular sparkly halo. Scientists believe the merger with Gaia-Enceladus was the first and the biggest one. This galaxy’s gas served as fuel for the star-forming processes of our own galaxy, but it did create a bit of a mess, stealing some ancient red stars from the body of Milky Way. We got to know all this thanks to the Gaia Spacecraft and its discoveries.
M31, also known as Andromeda, is our closest neighbour and it’s on the course to merge with Milky Way. Measurements made with the help of Gaia Spacecraft allowed astronomers to create an estimate timeline for the event – it’s supposed to happen in about 4.5 billion years. Other calculations suggest Milky Way would hit Andromeda earlier in just 4 billion years, but it doesn’t really make that big of a difference since our galaxy will still become Andromeda’s breakfast.
If you think Milky Way was a bit of a hungry beast, wait till you hear about Andromeda’s diet. The M31 galaxy has existed for over 10 billion years eating up smaller galaxies during all this time. A study published in Nature delves into the complex structure of the Andromeda galaxy’s stellar halo that suggests that it has gone through at least two big mergers apart from numerous smaller ones. One happened when the galaxy was still quite young, while the other one was quite recent – just a few billion years ago!
Clash of the Titans
Astronomers believe the future collision will be a fierce, nearly apocalyptic event that will tear both of the galaxies apart. Just because both of them are natural galaxy-eaters and will bite pieces from each other in a very vicious manner. Scientists have found numerous remnants from previous meals of Andromeda, all of which became part of her galactic halo in a form of globular clusters. Scientists predict that the collision of two galaxies will be highly destructive and there will be nothing left of their beautiful spiral disks. On a more cheerful note, if humanity survives to observe the event, we will see billions of new stars in the skies above Earth.