The United Nations has declared 30 June to be International Asteroid Day, and ESA is joining other space agencies, astronauts, scientists and even rock stars for a 24-hour global telethon.

To mark this year’s Asteroid Day, ESA will take part in a unique, round-the-clock telethon that will be broadcast worldwide from Luxembourg, as well as live on the internet, highlighting the threat from asteroids and other ‘near-Earth objects’ that pose an impact risk.

Hazardous space rocks

In December 2016, the United Nations proclaimed the last day in June as International Asteroid Day to raise public awareness about asteroid impact hazards. This date, 30 June, marks the anniversary of the largest-ever, in modern times, atmospheric entry of a meteoroid (thought to be a comet or small asteroid), which exploded over the Tunguska region of Siberia in 1908. With an estimated size of over 40 m, it devastated an uninhabited area the size of a major metropolitan city.

Detritus in our Solar System such as asteroids and other near-Earth objects – basically, anything whose orbit brings it close to Earth – impact Earth every day. Most of them are little more than small particles of dust and they burn up harmlessly in the atmosphere (have you ever seen a shooting star?).

However, larger ones, such as Tunguska – or the 20 m diameter object that exploded high over Chelyabinsk, Russia, on 15 February 2013, with 20–30 times the energy of the Hiroshima atomic bomb – can threaten human health and property.

“When Tunguska occurred 109 years ago, humanity was not ready to predict such events,” says Rüdiger Jehn, Co-Manager for NEO activities in ESA’s Space Situational Awareness (SSA) programme.