The Milky Way is home to hundreds of billions of stars arranged in a glorious spiral pattern. But beyond the obvious spiral, our galaxy has other physical characteristics. It's divided into a galactic bulge, a galactic disk, and a galactic halo.

The disk is further divided into a thin disk and a thick disk. They're not only structurally different, but their stellar populations and other characteristics are different.

The thin disk contains young stars, and middle-aged stars like our Sun. It holds the spiral arms, where our Solar resides and also holds most of the Milky Way's gas and dust and is where young stars form. It also has higher metallicity, generated by previous generations of stars that have lived and died.

The thick disk is more puffy and diffuse than the thin disk. It holds ancient stars, and almost no new stars form there.…