Alright, people…time to finish off our exploration of the Milky Way Galaxy, our home in the cosmos!
For the past nine weeks, we’ve covered everything from how our galaxy was “discovered” to how it may have formed. But there’s so much more to explore–and, starting next week, we’ll begin covering the vast universe of galaxies beyond our own!
But before we do that…I want to wrap up our discussion of our own galaxy with an overview to tie the last nine posts together.
(By the way, has anyone noticed I actually managed to chug out a post a week for the entire Milky Way “module”? I’m a bit impressed with myself for that!)
The Milky Way–our home galaxy–is a spiral galaxy, a classification I often describe as pinwheel-shaped.
The main difference between a spiral galaxy’s shape and a pinwheel’s shape is that spiral galaxies, like the Milky Way, only have two main arms. For the Milky Way, those are the Scutum-Centaurus arm and the Perseus arm. If you study the image above, you’ll notice that all the other arms are a bit wispier, and most branch off from the main arms.
There’s just one problem, though…
How do we even know that this image is an accurate depiction of our galaxy? How do we know that the Milky Way has spiral arms?