galàxies
Galàxies are gravitationally bound systems that contain stars, stellar remnants, gas, dust, and dark matter. They range from dwarfs with a few million stars to giants with hundreds of billions. Galàxies are the fundamental building blocks of the universe’s large-scale structure and host most of the visible matter.
They are commonly categorized by morphology into elliptical, spiral, and irregular types. Elliptical galaxies have smooth,
Formation and evolution: Galàxies form within dark matter halos in the early universe as gas cools and
Observations and significance: Distances to galaxies are measured using standard candles and redshift; Hubble’s law relates
Notable examples include the Milky Way, the Andromeda Galaxy (M31), and the Triangulum Galaxy (M33).