andromeda collided with the milky way in about 4 billion years.
andromeda collided with the milky way in about 4 billion years.
when does andromeda collide with the milky way?
in about 4 billion years
the andromeda galaxy is approaching the milky way at about . it has been measured approaching relative to the sun at around as the sun orbits around the center of the galaxy at a speed of approximately . this makes the andromeda galaxy one of about 100 observable blueshifted galaxies. andromeda galaxy's tangential or sideways velocity with respect to the milky way is relatively much smaller than the approaching velocity and therefore it is expected to collide directly with the milky way in about 4 billion years. a likely outcome of the collision is that the galaxies will merge to form a giant elliptical galaxy or perhaps even a large disc galaxy. such events are frequent among the galaxies in galaxy groups. the fate of the earth and the solar system in the event of a collision is currently unknown. before the galaxies merge, there is a small chance that the solar system could be ejected from the milky way or join the andromeda galaxy.
andromeda galaxy
the andromeda galaxy is approaching the milky way at about as indicated by blueshift. however, the lateral speed (measured as proper motion) 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 timeframe amounts to only 1/3,000th 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 = 0.000017 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 and a half billion years.
andromeda–milky way collision