I have been saving astronomical pictures I like from APOD, HEASARC, ESA/Hubble, and Bad Astronomy for about 6 years now. The number is now ~1800 pictures. Most of the ~600 pictures in the Extragalactic folder are galaxies or clusters of galaxies. I was looking through these the other day, and, with an extremely overactive imagination, discovered several examples of Kardashev Type III civilizations!
This galaxy is around 26 Mpc (megaparsec, around 3 million light years) away, on the outskirts of the Virgo Cluster. There does not appear to be any other nearby galaxy that could have caused the jet as a tidal effect.
When One Shield Is Not Enough!
This galaxy is NGC 474, around 30 Mpc away, and is called a shell galaxy. There are not many of these, but I think that more sensitive telescopes will find more. The two galaxies together form Arp 227.
Nearby is another galaxy (NGC 467) also with faint shells. Here's a pic of all 3 galaxies:
What Is This???Hoag's Object. But it doesn't have an NGC number or appear in any other catalogue of galaxies -- because IT IS SO WEIRD!
So maybe a bar instability cleaned out the space? Hard to believe that has only happened once -- no other galaxy looks like this one. Normal ring galaxies are formed when one galaxy punches through the center of another, like these two examples:
APOD has featured Hoag's Object 4 times, most recently here.
It just ain't right! Must be an advanced alien civilization! But, what are they building???
A Project Gone Bad
This is actually one of my favorite galaxies of all time. NGC 1275 is the largest galaxy in the Perseus Cluster (Abell 426). It is around 73 Mpc away. Even at that distance, the Perseus Cluster is the brightest extragalactic X-ray source in the sky. There have been several great pictures of NGC 1275 since Hubble went up, and I still can't figure what the hell is going on. Here's more pix, the latter 2 with overlays taken in non-optical wavelengths:
So, will our galaxy someday support a Kardashev Type III civilization? I guess I hope so. Just get human civilization through the next 30-40 years and we'll be ready to get right on it!