Large Asteroid to Safely Pass Earth on Sept. 1
Jet Propulsion Laboratory
August 17, 2017
Asteroid Florence, a large near-Earth asteroid, will pass safely by Earth
on Sept. 1, 2017, at a distance of about 4.4 million miles, (7.0 million
kilometers, or about 18 Earth-Moon distances). Florence is among the largest
near-Earth asteroids that are several miles in size; measurements from
NASA's Spitzer Space Telescope and NEOWISE mission indicate it's about
2.7 miles (4.4 kilometers) in size.
"While many known asteroids have passed by closer to Earth than Florence
will on September 1, all of those were estimated to be smaller," said
Paul Chodas, manager of NASA's Center for Near-Earth Object Studies (CNEOS)
at the agency's Jet Propulsion Laboratory in Pasadena, California. "Florence
is the largest asteroid to pass by our planet this close since the NASA
program to detect and track near-Earth asteroids began."
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. 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. The resulting
radar images will show the real size of Florence and also could reveal
surface details as small as about 30 feet (10 meters).
Asteroid Florence was discovered by Schelte "Bobby" Bus at Siding Spring
Observatory in Australia in March 1981. It 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. Florence will brighten to 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.
Radar has been used to observe hundreds of asteroids. When these small,
natural remnants of the formation of the solar system pass relatively
close to Earth, deep space radar is a powerful technique for studying
their sizes, shapes, rotation, surface features and roughness, and for
more precise determination of their orbital path.
JPL manages and operates NASA's Deep Space Network, including the Goldstone
Solar System Radar, and hosts the Center for Near-Earth Object Studies
for NASA's Near-Earth Object Observations Program, an element of the Planetary
Defense Coordination Office within the agency's Science Mission Directorate.
More information about asteroids and near-Earth objects can be found at:
For more information about NASA's Planetary Defense Coordination Office,
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Jet Propulsion Laboratory, Pasadena, Calif.
Laurie Cantillo / Dwayne Brown
NASA Headquarters, Washington