Largest asteroid to fly past Earth this year is coming soon — and it’s huge Dawn Jorgenson, Digital Content Editor, Graham Media Group Published: Tags: Telescope pointed at a starry sky. (Photo by Lucas Pezeta from Pexels.) The largest asteroid known to be passing near Earth this year will also be one of the fastest rocks to cruise past our planet, and it’s all happening March 21. Before you panic, just know this: though it’s been classified as a Potentially Hazardous Asteroid -- because of its size and frequency of passing near Earth -- but there’s no risk of impact, according to EarthSky.