2002: On 15 April 2002, the European Space Agency reported that two asteroids had passed close by Earth, at distances of 1.2 and 3 times the distance to the Moon.
By monitoring known asteroids, astronomers can predict which may collide with Earth. ESA continues to study ways in which its missions can assist in monitoring unseen but potentially hazardous asteroids.
A discovery, made using data from ESA's Infrared Space Observatory (ISO), showed that there could be nearly two million asteroids larger than one kilometre in the main asteroid belt, between Mars and Jupiter.
When the asteroids remain in the main-belt, they pose no danger to Earth. However, they can be thrown into different orbits by collisions with other asteroids or by the influence of Jupiter's gravitational field. If their new orbits cross the Earth's orbit, they could one day collide with our planet.
Modh meán
13 April
12 April
11 April
Fan suas chun dáta
Liostáil lenár nuachtlitir chun an nuacht is déanaí, nuashonruithe misin, agus léargas eisiach a fháil go díreach i do bhosca isteach. Bí ar an gcéad duine a bheidh ar an eolas faoinár dtionscadail agus ár ndul chun cinn atá le teacht.