When I was a kid, the biggest dinosaur was the brontosaurus. Later scientists declared that there was no such beast, and renamed it apatosaurus, the post office notwithstanding.

Well, you can argue until the cows come home, but the bottom line is that scientific knowledge is always advancing. Except that Pluto is still a planet, dammit.

We’ve known for a long time that our galaxy was a spiral, similar to the great “nebula” in Andromeda, but over my lifetime, our knowledge of our home has increased exponentially, and it’s hard to keep abreast of all the changes.

(Image found at Nature.)

First off, we now know our galaxy is a barred spiral, with an elongated central core. Moreover, instead of being a lone unit in space as was once thought, our galaxy is only part of a large dynamic neighborhood of at least 26 dwarf galaxies (some of which are being torn apart and consumed, like the Saggitarius star stream), 157 globular clusters, a massive halo of stars with almost the mass of the main disk itself which may extend as far as the Magellanic clouds, powerful x-ray and gamma-ray bubbles issuing from a central black hole, and a dark-matter halo with a radius of 100 kiloparsecs. And that’s just today; just imagine what we’ll know tomorrow.

The Old Wolf has spoken.