A strange attractor

We've had a sudden warm, sunny spell -- very unusual for mid-April in upstate New York, where the weather can remain chilly well into May and we've sometimes had snow on Mother's Day.  One thing you have to say for upstaters; we don't waste these opportunities when they come.  There was a steady stream of runners and cyclists on the road past my house, and as for me, I spent the day working in the front yard putting in some new raised-bed gardens.  The result was (1) some landscaping that's going to be gorgeous when it's full of flowers in a couple of months, (2) sunburned back and shoulders (not severe, fortunately, but a little redder than they should be), and (3) sore muscles.

The cloudless skies continued into yesterday evening, which brought me outside once again -- this time to enjoy a glass of wine and watch the stars.  As I sat there, the darkness deepening around me, I was once again astonished by how beautiful a clear night sky is.  It amazes me that anyone can look up into the star-spangled blackness and not be awestruck.  I looked at those hundreds of little pinpoints of light -- each one actually a blazing sun, some of them orders of magnitude bigger than our own -- and wondered, as I have so often before, which of them have planets, and which of those planets might host life.

Then, it struck me how little of the universe I'm actually seeing.  Regular readers of Skeptophilia might recall my posting this image of the Milky Way, but it's worth seeing again:

[Image licensed under the Creative Commons Pablo Carlos Budassi, Milky way map, CC BY-SA 4.0]

I know it's hard to read the text, so I encourage you to go to the site where it comes from, and spend some time zooming in on it.  In particular, find the little circle in the lower center that's labeled "Naked Eye Limit."

Every individual star you have ever seen without a telescope is inside that little circle.

Even our own galaxy is largely a mystery to us.  There's an enormous black hole at its center called Sagittarius A* ticking and purring (I can't help hearing that in Carl Sagan's memorable voice), which we know of by its x-ray and gamma ray signature; much of what else we know was either discovered in the last century using powerful telescopes, or else is inferential.

Amongst the inferential bits is one of the oddest mysteries in astrophysics; the Great Attractor.  The Great Attractor is the apparent center of gravity of the Laniakea Supercluster, a huge assemblage that contains not only the Milky Way and its nearby companions, the Andromeda Galaxy and the Magellanic Clouds, but one hundred thousand other galaxies, each containing something on the order of one hundred billion stars.  (Once again invoking Carl Sagan's voice for emphasis.)

If your mind boggles at this, so does everyone's.  Or should.  But the weirdest thing is that we have no idea what the Great Attractor actually is.  It is "inconveniently placed," as one astronomer put it (well aware that stating it that way is about as ridiculously anthropocentric as you can get).  Between us and it is the center of the Milky Way, so we can't currently see it, and won't be able to for another hundred million years, at which point the Solar System will have orbited around the galactic center and will be pointing toward whatever the Great Attractor is.  It may be a huge collection of galaxies, with enough mass to gravitationally attract everything in the region; it may be something odder.

We simply don't know.

And if that's not enough for you, it was recently discovered that the Great Attractor itself is moving toward something even bigger, the Shapley Supercluster, which is the largest gravitationally-bound structure we know of.

At that point in my musings, my glass of wine was empty, and I felt minuscule enough for one night.  Sitting there, looking up into the vastness of space, left me (as it always does) with a keen awareness of the insignificance of all of our little Earth-bound problems.  It didn't, and doesn't, bother me; being overawed by the grandeur of it all is hardly a bad thing.  It's comforting to know that as we toil through our busy little lives down here, overhead the majestic cosmos still soars, extending in every direction farther than we can see, or even imagine.

I think I'll go outside again this evening.

****************************************