World Asteroid Day: Know date, significance, history and more about the unique day World Asteroid Day: The special day is observed to celebrate the anniversary of the Siberian Tunguska event. Read on to know more about it Updated: Tue, 29 Jun 2021 10:19 PM IST Pixabay New Delhi | Jagran Lifestyle Desk: World Asteroid Day also known as International Asteroid Day is a UN-sanctioned annual global event that is observed on June 30th. World Asteroid Day: History On June 30 in 1908, the most harmful known asteroid-related event took place which was the Siberian Tunguska event. And it's the anniversary of this event, that World Asteroid Day is observed annually.