The keyhole passage is a region of space near Earth where the planet’s gravity can still shift an asteroid’s orbit.
Even if an asteroid is deemed safe now, the rock can threaten the planet at a later date if affected by the keyhole passage.
Dr Paek said: “A keyhole is like a door — once it’s open, the asteroid will impact Earth soon after, with high probability
One such asteroid is expected to scrape by the Earth nine years from now on April 13.
The 1,100ft-wide (340m) Asteroid Apophis will come hurtling past Earth at more than 67,000mph through a region of space where geostationary satellites are in orbit.
source: express.co.uk