Watch 20 Years of Asteroid Discoveries Unfold in Seconds! ☄ maps their positions over time, ending with a full snapshot of every known asteroid from 1999 to 2018. Each dot in this animation represents a known near-Earth objects (NEOs) – asteroids and comets that come close to our planet’s orbit – over a 20-year span, from 1999 to 2018. NASA’s NEO Observations Program has detected over 18,000 NEOs, with an average discovery rate of 40 per week! That’s more than 95% of all known near-Earth asteroi