<P> The Andromeda--Milky Way collision is a galactic collision predicted to occur in about 4 billion years between the two largest galaxies in the Local Group--the Milky Way (which contains the Solar System and Earth) and the Andromeda Galaxy . The stars involved are sufficiently far apart that it is improbable that any of them will individually collide . Some stars will be ejected from the resulting galaxy, nicknamed Milkomeda or Milkdromeda . </P> <P> The Andromeda Galaxy is approaching the Milky Way at about 110 kilometres per second (68 mi / s) as indicated by blueshift . However, the lateral velocity is very difficult to measure with a precision to draw reasonable conclusions: a lateral speed of only 7.7 km / s would mean that the Andromeda Galaxy is moving toward a point 177,800 light - years to the side of the Milky Way ((7.7 km / s) / (110 km / s) × (2 540 000 ly)), and such a speed over an eight - year time frame amounts to only 1 / 3000 of a Hubble Space Telescope pixel (Hubble's resolution ≈ 0.05 arcsec: (7.7 km / s) / (300 000 km / s) × (8 y) / (2 540 000 ly) × 180 ° / π × 3600 = 0.000 017 arcsec). Until 2012, it was not known whether the possible collision was definitely going to happen or not . In 2012, researchers concluded that the collision is sure using Hubble to track the motion of stars in Andromeda between 2002 and 2010 with sub-pixel accuracy . Andromeda's tangential or sideways velocity with respect to the Milky Way was found to be much smaller than the speed of approach and therefore it is expected that it will directly collide with the Milky Way in around four billion years . </P>

When does andromeda collide with the milky way