So if the Sun came from the dwarf, we’d be orbiting the Milky Way at that angle ourselves! Studies of the Sun’s motion relative to the plane of the Milky Way (using the stars, globular clusters, other galaxies, and many other sources) make it a rock-solid certainty that the Sun’s orbit is in fact of the Milky Way. First, the plane of the solar system (defined, really, by the plane of the Earth’s orbit) is tilted with respect to the Milky Way’s plane by about 60 degrees or so.
If we belong to the dwarf galaxy, what are the odds that at this point in time we’d be almost exactly in the center of the plane of the Milky Way?
In other words, at one point in Earth’s orbit, you can draw a line from the Earth through the Sun and it will pass very near the center of the Milky Way (if you were at the Galactic center, you’d see our solar system "edge-on").
If our solar system were aligned with the dwarf stream, that wouldn’t happen (from the Milky Way’s center, the solar system would appear to be "face-on").
“Remarkably, stars from Sagittarius are now raining down onto our present position in the Milky Way. We have to re-think our assumptions about the Milky Way galaxy to account for this contamination.” Wow, that sounds like Majewski, the lead author of the scientific paper, agrees that the Sun must come from the dwarf galaxy, doesn’t it? The vast majority are, to be sure (or else we would have discovered the interloping galaxy a long time ago), and astronomers will have to be careful when looking at individual stars. To be fair, this is from the original press release.
But the way it’s placed in the Viewzone article is misleading. I’m not a fan of attacking the messenger, but sometimes it pays to look at someone’s pedigree when they are making a huge claim like this.