IC 4378

IC 4378 is a lenticular galaxy in the constellation Centaurus about 198 million ly from Earth. It spans roughly 89,000 ly, about the width of our Milky Way. The light reaching us tonight left it about 198 million years ago.

Because its light is 198 million ly from home, you are seeing IC 4378 as it looked roughly 198 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).