IC 3556

IC 3556 is a lenticular galaxy in the constellation Coma Berenices about 344 million ly from Earth. It spans roughly 56,000 ly, about 56% of our Milky Way's width. The light reaching us tonight left it about 344 million years ago.

Because its light is 344 million ly from home, you are seeing IC 3556 as it looked roughly 344 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).