For International Asteroid Day, check out scientists’ plans for keeping dangerous space rocks from hitting Earth

  • Recognised in 2016 by the UN, this day is about educating people on the threat of asteroids and how to prepare for the possibility that one may head towards us
  • We explain what these rocky objects are and what methods have been proposed for keeping the planet safe from them
Doris Wai |

Latest Articles

Taylor Swift’s Eras tour concert film gets worldwide release

Hong Kong toddler in hospital after accidentally consuming suspected meth

Rosaryhill School sponsor proposes ‘sending secondary students to another aided institution’

SOTY 22/23: Visual Artist second place winner finds inspiration in Hong Kong, family harmony

Hong Kong school facing risk of closure offers HK$10,000 ‘scholarship’ for Primary One

Asteroids are small, rocky objects that orbit the sun. Photo: Shutterstock

International Asteroid Day is observed around the world on June 30. Founded after the release of the 2014 sci-fi film 51 Degrees North, which explores what would happen if an asteroid were to strike Earth, this day seeks to raise awareness about the threat of asteroids and what we can do in the event that one might hit our planet.

Read more about asteroids in the graphic, and should one ever head our way – the likelihood is rare – check out the methods scientists have proposed to keep us safe.

Graphic: Doris Wai

1. Zapping it

This may seem like an incredulous idea, but scientists think one way to send an asteroid away from Earth is by surrounding it with sunlight-powered lasers that zap its surface so parts of it vaporise. This causes the asteroid to release a stream of material, called ejecta, that results in the asteroid accelerating in the opposite direction of its intended path.

8 answers to your burning questions about asteroids

2. Crashing a spacecraft into it

Unlike what films often depict, an asteroid cannot be shot down in the last few minutes or hours before impact. However, its course can be altered, for example, by launching a spacecraft to hit it with enough impact to change its course so it no longer poses a threat to us.

Launched last November, Nasa’s Double Asteroid Redirection Test (DART) mission will see if intentionally crashing a spacecraft into an asteroid is an effective way to change its course. Photo: EPA-EFE/NASA

3. Tugging it away

Another way scientists are looking to divert an approaching asteroid is to send a special spacecraft called a gravity tractor device. After flying it near the asteroid, the tractor could potentially tug the asteroid off course using its own gravity. According to calculations by two Nasa scientists, Ed Lu and Stan Love, it would take about a year for the spacecraft to drag a medium-sized asteroid – measuring 200 metres across and weighing 60 million tonnes – away from Earth’s path.

Fridge-sized asteroid hit Earth two hours after it was first spotted

Keep in mind that these methods are still being researched – none have been proven to work. They will require at least years, if not decades to test and develop.

This is why we must closely observe the solar system and develop technology to detect asteroids that may be headed our way. While dangerously large space rocks only hit Earth’s surface every several thousand years, it is better to be safe than sorry.

Sign up for the YP Teachers Newsletter
Get updates for teachers sent directly to your inbox
By registering, you agree to our T&C and Privacy Policy