I know you can’t see this comment but maybe someone else will find it useful

Just like how a siren changes pitch when it’s coming from a vehicle passing by due to the Doppler effect, the same thing happens to moving light sources due to relativistic effects.

Usually astronomical objects are redshifting because the universe is expanding and are thus receding away from Earth’s frame of reference. Most of them are forever unreachable even if we could travel at the speed of light.

Something blueshifting means it’s coming closer from Earth’s frame of reference. In some cases, this could result in the galaxy colliding with ours, such as the hypothesized collision between the Andromeda Galaxy and the Milky Way