Monday, January 02, 2012

Great video and the end of the world riff

Here are some quick thoughts about the whole EOTW notion, celestial mechanics and a really cool video.
When the night sky was free of urban light pollution, the Milky Way was clearly visible. A time lapse video of the night sky taken in Chile, in a place outside of Santiago where the Milky Way is still clear, as the Earth rotates, the orientation of the Milky Way changes:  where at an early nighttime point in time it is diagonally across the sky, pointing at maybe 10 o'clock, by the time the sun comes up, it is nearly perpendicular to the horizon, at twelve o'clock.
Here is the video- it is really great, intended to capture comet Lovejoy, which is spectacular, but you can see the Milky Way clearly as well:
The orientation of the Milky Way is strongly noted by the "dark road" down the middle. This is actually dust that obscures the stars towards the center of the galaxy, which make the "river" of the distant galactic glow of stars seem like it has two lanes.
At any rate, throughout most of human history before city lights, this view of the sky was everyone's view, including the Mayans.
And, just like the moving orientation of the galaxy through the sky can be expressed in terms of a clock's hand, so can longer periods of time be told by changes that occur in that orientation.
The galaxy is a large wheel, with a thickness, and it seems to spin mightily. That dark band, The Great Rift, lies between us and the wheel's hub, where we are about a third of the way in from the edge of the galaxy. Now, the solar system rides around that hub, in a peculiar way. There is the revolution around the galactic center, but also an up and down, in and out movement. It's like the solar system is on the back of a merry go round horse that spins on an axis from its nose to its tail. Relatively, the distances are very large, so our star and its planets are tiny grains on the horse's saddle, moving in tight little orbits around the big grain that is the sun.
Our planet travels in an ellipse on a plane around the sun, which travels along that slinky-shaped path around the galactic center, in a way where our solar orbit's planar orientation to the plane of the galaxy is not coincident or parallel with the predominant plane of the galaxy. Our planet rotates on a slightly tilted axis relative to our orbit, but not so tilted as to account for the side view of the galaxy to go like a windshield wiper halfway across the sky.
But the sum of the earth's tilt plus the skew of the plane of the solar system relative to the galactic plane AND angle from our position along the "slinky path" is why we see the Sun coming up basically straight up "inside" the Dark Rift, as the comet tail fades in the dawn.
Now, look carefully at that part of the video. What did the ancients see?
The sun rising into the blackest part of the sky, into the "jaws" of the giant dragon/beast, about to be devoured at the very moment the sun's own brilliance obliterates the awful scene!
What can we imagine what they'd be see now, given some idea of how they imagined?
The sun, armed with the spear-like comet, slaying the dragon? Or climbing up into the rift, where it appears like a large high-backed chair, a throne (!) almost climbing up like a small child, and taking his place? Wielding a sword, or sceptre (the comet) to it's right, with which to banish the darkness!
And we see the comet, it's tail is nearly parallel with the galactic plane, so this gives us some information locally about the orientation of the entire galaxy, all without advanced optics.
Amazing sight, I can't help feeling thankful.

[edit, added links]
A description of the solar system's path around the galaxy from a physics blog:

Additional information, noting the spiral "slinkk" path:

"Local" motion of solar system, and nature of the heliosphere


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