Stars & Galaxies
From the birth of stars to the grand design of galaxies — discover the objects that light up our Universe.
The Life Cycle of a Star
1. Stellar Nebula
Clouds of gas and dust collapse.
2. Protostar
Gravity pulls material into a young star.
3. Main Sequence
Hydrogen fusion powers the star.
4. Red Giant
The star expands and cools.
5. Planetary Nebula
Outer layers drift away from the core.
6. White Dwarf
The core remnant cools over time.
Types of Stars
Stars come in a variety of sizes, temperatures, and colors.
Types of Galaxies
Spiral
Disk-shaped with prominent spiral arms.
Elliptical
Round or oval with little internal structure.
Irregular
No defined shape; often chaotic.
Featured: The Milky Way
Our home galaxy is a barred spiral with more than 100 billion stars, planetary systems, dust lanes and dark matter.
Keep Learning
Star Birth: Inside Nebulae
Explore the stellar nurseries where stars are born.
Read Article
The Sun: Our Closest Star
Learn how the Sun powers life on Earth.
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Galaxy Clusters
Discover the Universe's largest gravitationally bound structures.
Read Article
Measuring the Cosmos
See how astronomers use light to reveal cosmic secrets.
Read Article