Definitions

You’ve seen the words. You’ve heard them used. Now you finally understand what they actually mean.

Galaxy
Discover what galaxies are, how they form, and why these vast collections of stars reveal the structure and history of the universe. Read more...
Milky Way
Explore the Milky Way, the galaxy that contains our Solar System, and discover its stars, spiral arms, and place in the universe. Read more...
Universe
Explore the universe, the vast expanse that contains every galaxy, star, planet, and the physical laws that shape everything known to exist. Read more...
Astronomy
Discover how astronomy explores planets, stars, galaxies, and the universe while expanding humanity's understanding of space and our cosmic origins. Read more...
Planet
Discover what defines a planet, how planets form, and why these remarkable worlds help scientists understand our Solar System and the universe. Read more...
Sun
Discover the Sun, the star at the center of our Solar System, and learn how it powers life on Earth and shapes our cosmic neighborhood. Read more...
Moon
Discover Earth's Moon, its phases, tides, history, human exploration, and why it remains one of the most fascinating objects in our Solar System. Read more...
Solar System
Discover the Solar System, its eight planets, the Sun, moons, asteroids, comets, and how our cosmic neighborhood was formed. Read more...