What is the local gravitational significance of detecting a blueshift from the Andromeda Galaxy?
Answer
Its gravitational pull overcomes cosmic expansion, signaling a future collision.
The detection of a blueshift from the Andromeda Galaxy, our closest large neighbor, carries crucial local significance. While distant galaxies generally show redshift due to universal expansion, Andromeda's blueshift indicates it is currently moving toward the Milky Way at a substantial speed (about 110 kilometers per second). This implies that the local gravitational attraction between the two galaxies is strong enough to overcome the general outward expansion of space on this scale, making it a member of our local group destined for a future gravitational interaction or collision.
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