NGC 3398

NGC 3398 is a spiral galaxy in the constellation Ursa Major about 135 million ly from Earth. It spans roughly 34,000 ly, about 34% of our Milky Way's width. The light reaching us tonight left it about 135 million years ago.

Because its light is 135 million ly from home, you are seeing NGC 3398 as it looked roughly 135 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).