Astronomers have a weird problem: In many ways, we can map the universe of galaxies around us better than we can the galaxy we live in.
It’s like being stuck inside a room in a house with big windows. You can clearly see lots of other houses outside, but the house you’re inside of is behind the walls, where you can’t see it.
Happily, this analogy only extends so far. We can see lots of things in our galaxy, the Milky Way, enough to get a sense of its shape, size, and structure. But you have to be clever about it.
For example, we know the overall shape is a flat, circular disk, and we’re in that disk near its midplane. We can see that on the sky; if you go outside when the Milky Way is high, you see it as a broad swath of fuzziness stretching across the sky.
We have other techniques to gauge its structure too, including mapping gas clouds (which can be observed with radio telescopes even when those clouds are clear across the galaxy from us) and the apparently very small motion of stars as they orbit the center.
A new study, though, presents ...