1,500 Asteroids We Didn't Know Existed

He walks through the timeline of asteroid discovery, and the numbers tell a story most people have never considered. In 1933, astronomers confirmed the first asteroid crossing Earth's orbital path. By 1970, that count had reached 30 near-Earth objects. Twenty years later, 135. By the turn of the millennium, over 400. Today, the estimated number of near-Earth objects larger than one kilometer in diameter sits at 1,500. That is not because more asteroids suddenly appeared. It is because our detection capabilities improved. The question he raises is simple: if we only recently developed the tools to see what is out there, how long has this threat existed without our knowledge? And what does that mean for our understanding of Earth's history, particularly the catastrophic events that shaped the Holocene?