Florence, a huge near-Earth asteroid, will pass safely by Earth on September 1, 2017, at a distance of about 4.4 million miles (about 18 Earth-Moon distances). It is amongst the biggest near-Earth asteroids ever recorded. To be more precise, measurements from NASA’s Spitzer Space Telescope and NEOWISE mission indicate it is about 2.7 miles in size.
Asteroid 1981 ET3, also known as 3122 Florence, or simply Florence, was discovered by Schelte “Bobby” Bus at Siding Spring Observatory in Australia, March 1981. It is named in honour of Florence Nightingale (1820-1910), the founder of modern nursing. The Minor Planet Centre has classified it as “potentially hazardous”.
While many known asteroids have passed by closer to Earth than Florence, all of those were estimated to be smaller. For example, earlier this year, a 10-foot-wide, near-earth object (NEO) passed by at an altitude of just 9,000 miles. Interestingly, its detection only occurred six hours before its nearest approach.
Florence is the largest asteroid to make a close-encounter since the program to detect and track NEO began in the 1990s. The 2017 encounter is the closest by this asteroid since 1890, and the closest it will ever be until after 2500. This is, therefore, an exceptional opportunity for scientists to study the asteroid up close.
When these fragments pass relatively close to Earth, deep space radar is a powerful technique to analyse their characteristics. It allows the study of their sizes, shapes, rotation, surface features and roughness, and a more precise determination of their orbital path.
Florence should be an excellent target for ground-based radar observations. NASA’s Goldstone Solar System Radar in California and at the National Science Foundation’s Arecibo Observatory in Puerto Rico are planning them. The resulting radar images will illustrate the real size of Florence. Besides, they could also reveal surface details as small as 30 feet in size.
Florence will brighten to the ninth magnitude in late August and early September. At this point, it will be visible in small telescopes for several nights. Binoculars in ideal conditions with minimal light pollution may be able to spot the asteroid.
While the nearest approach will be on September 1, you can start looking for the asteroid a couple of nights earlier. On August 27, Florence will be in the constellation Piscis Austrinus, reaching about 19 degrees above the southern horizon. Afterwards, it will move through the constellations Capricornus, Aquarius and Delphinus.
Asteroid Florence is travelling at 30,266 mph. Nonetheless, the distance will make it appear so slow that observers should keep observing the fairly bright asteroid for about 5 to 10 minutes to see any movement.
Are you hooked on stargazing? If so, you must try to catch a glimpse of this huge asteroid as it passes by Earth in the following couple of days!