Catastrophic galactic collision could send Solar System flying into space

January 4, 2019, Durham University
The Whirlpool Galaxy (M51a) and companion galaxy (M51b). This Hubble Space Telescope image represents a merger between two galaxies similar in mass to the Milky Way and the Large Magellanic Cloud. Credit: NASA, ESA, S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA)

New research led by astrophysicists at Durham University, UK, predicts that the Large Magellanic Cloud (LMC) could hit the Milky Way in two billion years' time.

The collision could occur much earlier than the predicted impact between the Milky Way and another neighbouring galaxy, Andromeda, which scientists say will hit our galaxy in eight billion years.

The catastrophic coming together with the Large Magellanic Cloud could wake up our galaxy's dormant black hole, which would begin devouring surrounding gas and increase in size by up to ten times.

As it feeds, the now-active black hole would throw out high-energy radiation and while these cosmic fireworks are unlikely to affect life on Earth, the scientists say there is a small chance that the initial collision could send our Solar System hurtling into space.

The findings are published today (Friday, 4 January) in the journal Monthly Notices of the Royal Astronomical Society.

Galaxies like our own Milky Way are surrounded by a group of smaller satellite galaxies that orbit around them, in a similar way to how bees move around a hive.

Typically, these satellite galaxies have a quiet life and orbit around their hosts for many billions of years. However, from time to time, they sink to the centre, collide and are devoured by their host galaxy.

This vibrant image from NASA's Spitzer Space Telescope shows the Large Magellanic Cloud, a satellite galaxy to our own Milky Way galaxy. Credit: NASA/JPL-Caltech/STScI

The Large Magellanic Cloud is the brightest satellite galaxy of the Milky Way and only entered our neighbourhood about 1.5 billion years ago. It sits about 163,000 light years from the Milky Way.

Until recently astronomers thought that it would either orbit the Milky Way for many billions of years, or, since it moves so fast, escape from our galaxy's gravitational pull.

However, recent measurements indicate that the Large Magellanic Cloud has nearly twice as much dark matter than previously thought. The researchers say that since it has a larger than expected mass, the Large Magellanic Cloud is rapidly losing energy and is doomed to collide with our galaxy.

The , led by scientists at Durham University's Institute for Computational Cosmology working with the University of Helsinki, in Finland, used the EAGLE galaxy formation supercomputer simulation to predict the collision.

Lead author Dr. Marius Cautun, a postdoctoral fellow in Durham University's Institute for Computational Cosmology, said: "While two billion years is an extremely long time compared to a human lifetime, it is a very short time on cosmic timescales.

"The destruction of the Large Magellanic Cloud, as it is devoured by the Milky Way, will wreak havoc with our galaxy, waking up the black hole that lives at its centre and turning our galaxy into an 'active galactic nucleus' or quasar.

"This phenomenon will generate powerful jets of high energy radiation emanating from just outside the black hole. While this will not affect our Solar System, there is a small chance that we might not escape unscathed from the collision between the two galaxies which could knock us out of the Milky Way and into interstellar space."

Simulation of the evolution of a galaxy similar to our own. The bright regions correspond to stars. The video shows the approach of a secondary smaller galaxy, a so-called satellite galaxy, that shortly afterwards gets devoured by the central galaxy. As the smaller galaxy gets destroyed, stars get ejected from the central region. Although the chances are small, our Sun could be one of those stars condemned to a long and lonely wander through the cold and dark intergalactic space. The movie shows a similar evolution to what researchers predict for the collision between our galaxy and the Large Magellanic Cloud. Credit: The Auriga project -- -- carried out by researchers at the Institute for Computational Cosmology, Durham University, UK, the Heidelberg Institute for Theoretical Studies, Germany, and the Max Planck Institute for Astrophysics, Germany.

The collision between the Large Magellanic Cloud and the Milky Way could be spectacular, the researchers say.

Co-author Professor Carlos Frenk, Director of the Institute for Computational Cosmology, Durham University, said: "Beautiful as it is, our Universe is constantly evolving, often through violent events like the forthcoming collision with the Large Magellanic Cloud.

"Barring any disasters, like a major disturbance to the Solar System, our descendants, if any, are in for a treat: a spectacular display of cosmic fireworks as the newly awakened supermassive black hole at the centre of our galaxy reacts by emitting jets of extremely bright energetic radiation."

According to the researchers, the merger of the two galaxies could be long overdue in cosmic terms.

Dr. Alis Deason, of Durham University's Institute for Computational Cosmology, said: "We think that up to now our galaxy has had only a few mergers with very low mass galaxies.

"This represents very slim pickings when compared to nearby galaxies of the same size as the Milky Way. For example, our nearest neighbour, the Andromeda galaxy, devoured galaxies weighing nearly 30 times more than those consumed by the Milky Way.

"Therefore, the collision with the Large Magellanic Cloud is long overdue and it is needed to make our galaxy typical."

Explore further: Magellanic clouds duo may have been a trio

More information: Marius Cautun et al, The aftermath of the Great Collision between our Galaxy and the Large Magellanic Cloud, Monthly Notices of the Royal Astronomical Society (2018). DOI: 10.1093/mnras/sty3084

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not rated yet Jan 04, 2019
Wow! Cosmic Apocalypse!
Run! Run & Hide!

So in a couple of billion years?
The Milky Way will devour the GMC? Just as it's done for a number of other satellite galaxies for 10+billion years or so.

When the cores mesh together, there will be a spate of new stars forming. Including possible radiation dangers... Two billion years from now...
Not my problem! Why should I panic over an imperfectly normal furball of galactic evolution?

Heck & shucks. Since in that tiny span of Time & Space, there is the improbability of the Earth recovering enough from the Anthropophagite Era to once again sustain a complex Biosphere?

Getting kicked out (red-carded?) of the scrum of scrambled galaxies, would reduce the danger of the Mature Earth being irradiated & sterilized.

Then later, once all the fuss & feathers have settled. The Solar System could be gravitationaly pulled back into the greedy Milky Way+ & rejoin one of the Outer Arms? For the remainder of it's existence.

3.7 / 5 (3) Jan 04, 2019
Boy you people at "Phys Org" are full of "Glade Tidings for Great Joy" today! Can't wait for your next sermon of impeding destruction of all mankind...
3 / 5 (8) Jan 04, 2019
.....and I had been hoping to spend the rest of my life swinging in my hammock from the gentle breezes blowing up from the valley below. Now I find in 1.5 billion years I'll be doing battle with the breezes of dark matter instead.

Just can't get any peace no matter how long I live.
3.4 / 5 (5) Jan 05, 2019
What Dark Matter? I don't see any Dark Matter. Do you?
2 billion years from now, they will STILL be looking for that Dark Matter.
not rated yet Jan 05, 2019
"As it feeds, the now-active black hole would throw out high-energy radiation and while these cosmic fireworks are unlikely to affect life on Earth, the scientists say there is a small chance that the initial collision could send our Solar System hurtling into space."

No worries! By 1 billion years most life had already gone extinct anyways, by 1.5 all of it has. By 2, forget about it!
not rated yet Jan 05, 2019
Getting kicked out (red-carded?) of the scrum of scrambled galaxies, would reduce the danger of the Mature Earth being irradiated & sterilized.

@rrwillsj What "Mature Earth" are you talking about? Earth's oceans will start evaporating in ~500 million years and in 1 billion years (tops) Earth will be completely sterile. Sterile as in dead. Not due to climate change (though it could accelerate the warming) but because the Sun is getting brighter and hotter as it ages.
Unless some huge and super advanced shading is devised and installed around the Earth, such as a vast fleet of light and heat reflecting satellites, the only habitable place in 500 million to 1 billion years will be Mars, and after about 2 to 2.5 billion years select moons of Jupiter and Saturn.
Another option might be to build a Dyson shell or swarm around the Sun before it gets too hot, which could be configured to allow the required sunlight to pass through at all times.
not rated yet Jan 06, 2019
The Earth being sterile due to Sun heating in a billion years is PURE SPECULATION. Impossible to predict our Sun's state in a billion years. It's all based on looking at other Sun's we know virtually nothing about, other than Lithium.
not rated yet Jan 06, 2019
Oh Sahstar! Damnit! You have me agreeing with the old coot.

Why will our Sun heat up & expand so soon? A billion years seems rather hasty for a small G-type star. But I could be wrong.
So let's adopt your idea of shading the Earth.
I know! Let's call it the ParaSol...

Of course any viable solution would require the existence, at that Time in the future, of a tool-using species.

Humanity's present intent is to exterminate as much of the Earth's lifeforms as our clever brains can devise a means.

At present, most big-brain intelligent species lack manipulative appendages.
& are trapped in the "Whale Dream".

Perhaps, deep into the future, this Earth will recover from the Matricide?
Restarting the long, slow, painful crawl of random evolution to achieve a new biosphere?

Then, perhaps a tool-using species will evolve? Not big sloppy brains like ours.
So obviously useless as an evolutionary dead-end.
But smarter brains, compact & complex like Avians?
Jan 06, 2019
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5 / 5 (1) Jan 06, 2019
Road trip!!
Da Schneib
1 / 5 (1) Jan 06, 2019
Clickbait. Like anyone cares what happens in a billion years.
not rated yet Jan 07, 2019
"Dark matter is a hoax."
- Republicans, if there's money at stake.

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