Astronomy Almanac >
 Home         
 Images         
 Questions         
 Almanac         
 Our Universe         
   Planets  
   Moons  
   Constellations  
   Stars  
   Messier Objects  
Galaxies  
   Nebulae  
 History         
   Timelines  
   Astronomers  
   Glossary         
Glossary > Red Giant Definition

Red Giant

A red giant is a star that has entered the phase of its lifecycle in which its outer layers have cooled and the temperature of it nuclear-fusing core has dramatically increased