A large near-Earth asteroid will pass safely by Earth on Sept. 1, 2017, at a distance of about 4.4 million miles, which is about 18 Earth-Moon distances.
Asteroid Florence is among the largest near-Earth asteroids that are several miles in size, according to NASA. Measurements from NASA's Spitzer Space Telescope and NEOWISE mission indicate it’s about 2.7 miles in size.
NASA says this relatively close encounter provides an opportunity for scientists to study this asteroid up close. Florence is expected to be an excellent target for ground-based radar observations, according to NASA.
Radar imaging is planned at NASA's Goldstone Solar System Radar in California and at the National Science Foundation's Arecibo Observatory in Puerto Rico, NASA says. The resulting radar images will show the real size of Florence and also could reveal surface details as small as about 30 feet.
Asteroid Florence, which was discovered by Schelte "Bobby" Bus at Siding Spring Observatory in Australia in March 1981, is named in honor of Florence Nightingale (1820-1910), the founder of modern nursing.
The 2017 encounter is the closest by this asteroid since 1890 and the closest it will ever be until after 2500, according to NASA.
NASA says Florence will brighten to the ninth magnitude in late August and early September, when it will be visible in small telescopes for several nights as it moves through the constellations Piscis Austrinus, Capricornus, Aquarius and Delphinus.
NASA contributed to this report.