An asteroid some 900 metres in diameter will have what in astronomical terms is deemed a 'close encounter' with earth today.
The nearest it will get to earth will be two million kilometres away, according to the US space agency, NASA.
It said there is no threat of a collision with our planet "now or for centuries to come".
But it said it is close enough for the asteroid - named 2001 FO32- to be classified as a "potentially hazardous asteroid".
NASA says it will pass by at about 124,000 kilometres per hour, faster than the speed at which most asteroids encounter Earth.
The asteroid will be at its closest to Earth at around 1600 GMT today, according to the Paris Observatory, France's largest astronomy research centre.
The asteroid will be brightest while it moves through southern skies.
Sixty-six million years ago an asteroid roughly twice the diameter of Paris crashed into Earth and wiped out 75% of life on the planet.