The largest asteroid to pass by Earth this year has made its closest approach, posing no threat of a cataclysmic collision but giving astronomers a rare chance to study a rock formed during the beginning of our solar system.

The asteroid was two million kilometres (1.25 million miles) away at its nearest, according to NASA—more than five times the distance between the Earth and the Moon but still close enough to be classified as a "potentially hazardous asteroid".

NASA tracks and catalogues such objects that could potentially slam into Earth and unleash enormous destruction, like the massive asteroid hit that wiped out 75 percent of life on the planet 66 million years ago.

Asteroid 2001 FO32, discovered 20 years ago, was too far to be that dangerous even as it reached its nearest point to Earth at around 1400 GMT Sunday, according to the Paris Observatory.