Asteroid Florence has close encounter with Earth, massive space rock passes 4.4 million miles from our planet

A huge asteroid, almost 3 miles wide in size, passed by just 4.4 million miles (7 million kilometres) from Earth on Friday. Asteroid ‘Florence’, named after Florence Nightingale, was at a distance which is equal to 18 times the distance between Earth and the moon. That was really a ‘close encounter’.

This was the closest a space rock of this size has come our planet since NASA first started tracking near-Earth objects, the US space agency said. Asteroid Florence was an unprecedented opportunity for astronomers to study it up close through ground-based radar observations.

According to NASA, nearly two-thirds of the near-Earth Asteroids (NEAs) have a satellite and if Florence has its own, chances are it could be spotted soon.“Despite some interference from moonlight, 3122 Florence should be fairly easy to spot in even modest backyard telescopes,” notes Kelly Beatty, a senior editor at Sky & Telescope magazine.

Late evening was the best time to view the asteroid as it was high overhead that time. Asteroid Florence reached peak brightness on September 1 and it is likely to remain nearly this bright for several days afterwards. It glided northward by a little less than the full moon's diameter each hour.

Florence appears so bright because it is one of the largest near-Earth asteroids. Also, a fairly bright surface reflects more than 20 per cent of the sunlight that hits it. The average reflectivity of moon is just 12 per cent.

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“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.

“Florence is the largest asteroid to pass by our planet this close since the NASA program to detect and track near-Earth asteroids began.”

The Florence asteroid was first spotted in 1981, but this flyby was the closest to Earth since 1890. On the night of March 2, 1981, asteroid hunter Schelte J Bus first discovered it in Siding Spring observatory. It orbits the Sun once every 859 days. Until 2,500, it won’t come this close to our planet again.

“Lots of these Earth-approachers are only visible for a matter of hours in amateur scopes before they precipitously fade from view”, according to Bob King writing in Sky & Telescope.

“They're just so tiny and move so fast. Not Florence. It's neither tiny nor in a terrible hurry. Matter of fact, it's a beast.”

“Some of you will be able to pick it up in binoculars, and anyone with a 4-inch or larger telescope should kill it.”

The asteroid is big enough to end life if it collides with the Earth, however, NASA had said that this won’t happen this week.A 2006 study claimed that a 0.6-mile-wide (1km) asteroid could lead to a mini ice age hit it hits Earth.