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Milky Way heading for catastrophic collision

(4 January 2019)

Hubble Space Telescope image representing a merger between two galaxies (M51a and M51b) 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)

The Milky Way is on a collision course with a neighbouring galaxy that could fling our Solar System into space.

The Large Magellanic Cloud could hit our galaxy in two billion years’ time

This galactic collision would happen much sooner than the predicted impact between the Milky Way and another neighbour, Andromeda, which scientists say will hit our galaxy in eight billion years.

Active black hole

The 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.

While these cosmic fireworks are unlikely to affect life on Earth, researchers say there is a small chance that the initial collision could send our Solar System hurtling into space.

Dark matter

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

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.

Solar System

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, which could have consequences for our Solar System.

Lead researcher Dr Marius Cautun, a postdoctoral fellow in our Institute for Computational Cosmology, said: “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 space.”

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