NGC 2921

NGC 2921 is a spiral galaxy in the constellation Hydra about 138 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 138 million years ago.

Because its light is 138 million ly from home, you are seeing NGC 2921 as it looked roughly 138 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).