One mode is like a bowl, with the galactic plane bending up all around; another is like a saddle, and the third is like the brim of a fedora hat, bent up in the back and down in the front, Blitz said at a briefing.
The various modes of warping correlate closely with the orbit of two satellite galaxies, known as the Large and Small Magellanic Clouds, that make a looping orbit around the Milky Way. As they go, they plow through a halo of dark matter that encircles the Milky Way, scientists said at a meeting of the American Astronomical Society.
Scientists have known about the Milky Way's warped nature for half a century, but they never knew the cause. The Magellanic Clouds were previously dismissed as suspects because they lacked the mass to influence our galaxy in their 1.5 billion year trip around it.
While the Magellanic Clouds' mass is small, they pass through the dark matter like ships going through an ocean, creating a cosmic wake powerful enough to make our galaxy bend and flap, Blitz said.
So the LMC and SMC aren't directly disturbing the gas disk that is warped, but they're disturbing the dark matter, which in turn affects everything else. I find that to be really elegant, as it is yet another example of how direct evidence isn't required, only indirect evidence and a solid chain of logic, just as with evolution. :)
I gave a talk for 7th graders lately about galaxies. This would've been nice info for the talk, if there were any pictures. One kid asked me, after I mentioned the Big Bang, what existed before the Universe. I at first took it as a creationist argument, but then I realized he probably just really wanted to know. My personal theory is that logarithmic time is more important than linear time, so there wasn't ever a "before," or even a time 0. I'm slightly on the fringe though, and I know it, and I'm definitely not a cosmologist (hence my calling it a "belief" and not even a "hypothesis"). They'd tell you that either there was nothing, or a previous universe, or maybe multiple hyper-universes (branes) collided to create our universe. But, and here's the key thing, we've got no way of knowing currently, so it's still just