Asteroid Florence is among the largest near-Earth asteroids that are several miles in size.

The space rock was discovered by astronomer Schelte ‘Bobby’ Bus at Siding Spring Observatory in 1981.

NASA’s Deep Space Network antenna captured new radar images of Florence as it safely flew past Earth on September 1, 2017.

At the point of closest approach, it was no closer than 4.4 million miles (7.0 million km, or about 18 Earth-Moon distances).

The radar images show Florence is approximately 4.5 km (2.8 miles) across and has two small moons 300-1000 feet (100-300 m) across.

“Florence is only the third triple asteroid known in the near-Earth population,” the NASA researchers said.

“The times required for each moon to revolve around Florence are also not yet known precisely but appear to be roughly 8 hours for the inner moon and 22 to 27 hours for the outer moon.”

“The inner moon has the shortest orbital period of any of the moons of the 60 near-Earth asteroids known to have moons.”

Although Florence is fairly round, it has a ridge along its equator, at least one large crater, two large flat regions, and numerous other small-scale topographic features.

The images also confirm that the asteroid rotates once every 2.4 hours, a result that was determined previously from optical measurements of its brightness variations.

Source: Sci News