NGC 4921

NGC 4921 is a spiral galaxy in the constellation Coma Berenices about 255 million ly from Earth. It spans roughly 150,000 ly, about the width of our Milky Way. It is receding from us at about 5,353 km/s.

Because its light is 255 million ly from home, you are seeing NGC 4921 as it looked roughly 255 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). Recession velocity from RC3 (de Vaucouleurs et al. 1991, via NASA/HEASARC, public domain). Distance computed by gravityfinder from redshift via Hubble's law (H0 = 70 km/s/Mpc).