PASADENA, Calif. - NASA said a large asteroid is expected to pass safely by the Earth on Friday morning.

Named "Florence," the asteroid is among the "largest near-Earth asteroids that are several miles in size." According to NASA's measurements, the asteroid is about 2.7 miles (4.4 kilometers) in size, or about 47 football fields wide.

NASA said Florence will pass within about 4.4 million miles of Earth. Scientists said other asteroids have been closer, but this one is the largest to have a close encounter with the planet since NASA began tracking near-Earth asteroids.

According to NASA, the close pass will give scientists a chance to study an asteroid up-close using ground-based radar observations.

"Florence" was first discovered in 1981, and named for Florence Nightingale.