Across
- 3. A theory explaining that spiral arms are not fixed structures but rather waves of high density (compression) that move through the galactic disk, triggering star formation as gas passes through them.
- 6. Using astrophysical masers (Microwave Amplification by Stimulated Emission of Radiation)—which are intense, naturally occurring radio sources—to map the structure of the galaxy and track star-forming regions
- 8. A large, spherical region surrounding the disk and bulge, containing old stars, globular clusters, and substantial dark matter.
- 10. A late-stage, luminous, cool star with a large radius, often found in globular clusters
- 13. A dense, roughly spherical group of tens of thousands to millions of old Population II stars, found primarily in the halo.
- 14. Young, blue, metal-rich stars (like our Sun) located in the disk and spiral arms.
- 15. A dense, opaque cloud of dust that obscures light from stars or brighter nebulae behind it, appearing as a dark patch
Down
- 1. A cloud of dust that scatters/reflects light from nearby stars, often appearing blue
- 2. Hypothesized first generation of stars formed after the Big Bang, containing no "metals" (elements heavier than helium), which have not yet been directly observed.
- 4. The area of the sky obscured by the dust and stars of the Milky Way's disk, which prevents clear optical observation of extragalactic objects behind it.
- 5. A cloud of ionized gas (primarily hydrogen) that emits its own light, appearing reddish-pink; these are often stellar nurseries
- 7. A tightly packed, football-shaped spheroid of mostly old Population II stars located at the center of the galaxy.
- 9. The flat, rotating component of the Milky Way, roughly 100,000 light-years across and 1,000 light-years thick, containing gas, dust, and young Population I stars.
- 11. A loosely bound, young grouping of hundreds or thousands of stars found in the galactic disk, often associated with emission nebulae.
- 12. Old, red, metal-poor stars found in the halo and bulge.