The Bad Astronomer writes "Astronomers have found the most massive galaxy in the near universe: an obese, bloated monster that may tip the cosmic scales at 13 trillion times the mass of the Sun, 20 times the mass of the entire Milky Way. The galaxy, called ESO 146-IG 005, sits at the center of a dense cluster of other (but much more lightweight) galaxies, and grew to its present size by eating the galaxies around it. In fact, the so-far undigested cores of at least five other galaxies are still easily seen in the cannibal's nucleus. Astronomers are having difficulty pinning down the galaxy's exact mass, but it's clearly the biggest bruiser within 1.5 billion light years of home."
I've never been canoeing before, but I imagine there must be just a few
simple heuristics you have to remember...
Yes, don't fall out, and don't hit rocks.