NGC 3998

NGC 3998 is a lenticular galaxy in the constellation Ursa Major about 51 million ly from Earth. It spans roughly 41,000 ly, about 41% of our Milky Way's width. It is receding from us at about 1,066 km/s.

Because its light is 51 million ly from home, you are seeing NGC 3998 as it looked roughly 51 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).