Stars and Galaxies Chapter 12. Stars Definition: a large ball of gas that emits energy produced by nuclear reactions in the star's interior Planets, comets, - ppt download
Galaxy | Definition, Formation, Types, Properties, & Facts | Britannica
Galaxy | Definition, Formation, Types, Properties, & Facts | Britannica
Public asked to define a galaxy › News in Science (ABC Science)
Composition of the Universe
What is a Galaxy? Definition and Types of Galaxies | Spiral Galaxies | BYJU'S
From EarthSky: “What is a galaxy?” | sciencesprings