Spiral Galaxies: Cosmic Pinwheels of Light

Spiral galaxies are shaped like giant pinwheels, with sweeping arms of stars and gas.
Our Milky Way is a barred spiral galaxy with four major arms.
Bright spiral arms are star nurseries, packed with young, hot, blue stars.
The central bulge contains older, redder stars and often a supermassive black hole.
Spiral galaxies make up about 60% of all galaxies we observe in the universe.
Dust lanes in their arms outline the structures and fuel future star formation.
The Andromeda Galaxy, our nearest large neighbor, is also a spiral.
Spiral arms are not fixed—they are density waves moving through the galaxy.
They can span over 100,000 light-years, yet rotate so slowly it takes hundreds of millions of years per spin.
Their graceful shapes make spiral galaxies some of the most iconic sights in astronomy.