What you learned in school
Physics textbooks described space as a perfect vacuum - absolutely empty between celestial objects. Students learned that space was pure nothingness punctuated only by stars and planets. This "empty space" concept was fundamental to understanding astronomy and physics, with space portrayed as a vast void through which objects moved.
What we know now
Physics textbooks described space as a perfect vacuum - completely empty between celestial objects. Students learned that space was just emptiness with occasional planets and stars. This "empty space" concept was fundamental to understanding the cosmos. Modern astronomy has discovered that space is filled with dark matter, dark energy, cosmic rays, interstellar gas and dust, magnetic fields, and various subatomic particles. What we once thought was empty is actually a complex medium that plays crucial roles in cosmic evolution and structure formation.