A UN-recognized global awareness day anchored to one of the most dramatic events in modern astronomical history.

On the morning of June 30, 1908, a stony asteroid roughly 50 to 60 meters wide exploded in the atmosphere above the Podkamennaya Tunguska River in remote Siberia, releasing an estimated 3 to 50 megatons of energy — enough to flatten around 80 million trees across 830 square miles of forest. Witnesses reported seeing a fireball nearly as bright as the sun, followed by a shockwave that broke windows hundreds of miles away and knocked people off their feet. No crater was ever found because the object disintegrated in the air and never reached the ground.

Asteroid Day was co-founded by astrophysicist and Queen guitarist Brian May, Apollo 9 astronaut Rusty Schweickart, filmmaker Grig Richters, and B612 Foundation president Danica Remy to raise public awareness about the asteroid threat and push for faster detection of near-Earth objects.

The UN officially designated it an international day of awareness and education in 2016.

Organizations like the Planetary Society and various planetariums often host public events and livestreams around it. We’ll update those events as soon as we hear about them!