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Milky Way's head-on collision
NASA astronomers say the Milky Way will collide with a neighbouring galaxy in 4 billion years.
NASA astronomers say they can now predict with certainty the next major cosmic event to affect our galaxy, sun and solar system: the titanic collision of the Milky Way galaxy with the neighbouring Andromeda galaxy.
The Milky Way is destined to get a major makeover during the encounter, which is predicted to happen four billion years from now. It is likely the sun will be flung into a new region of our galaxy, but our Earth and solar system are in no danger of being destroyed.
The solution came through NASA Hubble Space Telescope measurements of the motion of Andromeda, which is also known as M31. The galaxy is now 2.5 million light-years away, but it is inexorably falling towards the Milky Way under the mutual pull of gravity between the two galaxies and the invisible dark matter that surrounds them both.
Computer simulations derived from Hubble’s data show that it will take another two billion years after the encounter for the interacting galaxies to completely merge under the tug of gravity and reshape into a single galaxy similar to the kind commonly seen in the local universe.
NASA says although the galaxies will plow into each other, stars inside each galaxy are so far apart that they will not collide with other stars during the encounter. However, the stars will be thrown into different orbits around the new galactic center.
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