The biggest asteroid in more than a century has whizzed past Earth at a safe - but unusually close - distance.

Asteroid Florence and its two orbiting moons passed 4.4 million miles from the planet, its closest encounter since 1890.

It measures in at almost three miles wide - the size of 30 Egyptian pyramids stuck together - and experts predict that this was the closest the asteroid will be to Earth until 2500.

Astronomers at the Arecibo observatory in Puerto Rico have released a video of the fly-by, and NASA is using radar images to study the asteroid's real size.

Named after Florence Nightingale, the founder of modern nursing, the asteroid was discovered in 1981.


Although collisions with Earth are rare, an asteroid the size of a car hits the Earth's atmosphere about once a year. However, it burns up before reaching the surface.

"About every 2,000 years or so, a meteoroid the size of a football field hits Earth and causes significant damage to the area," NASA said.

"Finally, only once every few million years, an object large enough to threaten Earth's civilization comes along."

Thankfully, scientists are confident that Florence is not going to be one of them.