NGC 3871

NGC 3871 is a barred spiral galaxy in the constellation Ursa Major about 450 million ly from Earth. It spans roughly 120,000 ly, about the width of our Milky Way. The light reaching us tonight left it about 450 million years ago.

Because its light is 450 million ly from home, you are seeing NGC 3871 as it looked roughly 450 million years ago. The photons left before that much of history had passed, and are only now reaching us. This distance is estimated from the galaxy's redshift, so the lookback time is approximate.

Source: structural data (position, morphology, brightness, redshift) from OpenNGC (CC BY-SA). Distance computed by gravityfinder from redshift via Hubble's law (H0 = 70 km/s/Mpc).