Asteroid Day是什么时候？

Asteroid Day is a United Nations-sanctioned global awareness campaign held every year on June 30th, marking the anniversary of the 1908 Tunguska event — the largest asteroid impact in recorded history, which flattened 2,200 square kilometres of Siberian forest. Co-founded in 2014 by Stephen Hawking, astronaut Rusty Schweickart, Queen guitarist and astrophysicist Brian May, and others, it brings together scientists, educators, and citizens to highlight the importance of planetary defence. Count down the days until Asteroid Day with our live countdown timer.