What you learned in school
Astronomy textbooks taught that stars were perfect, unchanging celestial objects that would shine forever. Students learned from ancient Greek philosophy that the heavens were made of quintessence - a perfect fifth element - and that celestial bodies were fundamentally different from earthly matter. Stars were described as eternal fixtures in the sky, permanently fixed and unchanging since creation, representing divine perfection.
What we know now
Astronomy classes taught that stars were perfect, unchanging celestial objects that would shine forever. Students learned that stars were fundamentally different from planets - permanent fixtures in the sky. Ancient Greek ideas about celestial perfection influenced this teaching. Modern astronomy has revealed stellar evolution - stars are born in nebulae, live for millions to billions of years burning fuel, and die in various ways including planetary nebulae, supernovae, or collapse into white dwarfs, neutron stars, or black holes. Stars are dynamic objects with complex lifecycles.