The closest asteroid in over a century will pass by the Earth this Friday, September 1.

Asteroid Florence, which is about 2.7 miles wide, will pass safely by the Earth at a distance of around 4.4 million miles. That's about 18 times the distance to the moon.

The close encounter will allow NASA scientists to study the asteroid up close. It'll be the closest asteroid to pass by the Earth since 1890, and the closest an asteroid will pass until after 2500.

The asteroid is named for Florence Nightingale, the founder of modern nursing, and was discovered by the Siding Spring Observatory in Australia in 1981.

It will be visible through telescopes for several nights as it moves through the Piscis Austrinus, Capricornus, Aquarius and Delphinus constellations.

More information about asteroids, and the work NASA is doing, can be found at