Learn what the Local Group is, which galaxies it contains, and why it matters to our understanding of the universe.

Learn how galaxy clusters form, from dark matter collapse to gas heating, galaxy mergers, and the intracluster medium.

Learn what the Milky Way galaxy is, how it formed, what it contains, and where Earth fits inside this vast spiral system.

Learn how to find the Milky Way in the sky with simple stargazing steps, season tips, dark-sky advice, and constellations that act as guides.

Learn what the center of the Milky Way is, what lies there, and why astronomers study this dense, energetic region.

Explore how spiral arms form in galaxies, from density waves and gravity to star formation, dark matter, and galactic rotation.

Learn what the Galactic Center is, why it matters, and how astronomers study the dense, energetic heart of the Milky Way.

Learn what a galactic halo is, what it contains, and how it helps astronomers study galaxy formation, dark matter, and cosmic history.