Spaceflight Insider

Nearly 3-mile wide asteroid to pass close by Earth Sept. 1

Asteroid Florence will pass by Earth on Sept. 1, 2017, at a distance of 4.4 million miles (7 million kilometers). Image Credit: NASA / JPL-Caltech

Asteroid Florence will pass by Earth on Sept. 1, 2017, at a distance of 4.4 million miles (7 million kilometers). Image Credit: NASA / JPL-Caltech

A large rock will fly past Earth on Sept. 1, 2017, at a distance of 4.4 million miles (7 million kilometers). Asteroid 3122 Florence, named after modern nursing founder Florence Nightingale, is the largest object to make a close-encounter since NASA began tracking near-Earth objects (NEO) in the 1990s.

“While many known asteroids have passed by closer to Earth than Florence will on Sept. 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 estimated to be about 2.7 miles (4.4 kilometers) in diameter. Were an asteroid of that size to strike Earth, it would have worldwide effects. However, this particular rock is not expected to present a risk of collision with the planet anytime soon as its next close approach will not be until after the year 2500.

The Sept. 1, 2017, approach will allow scientists to study the asteroid with radar from the surface of the Earth. Amateur astronomers might also be able to get a peek at Florence, which will have an apparent magnitude of 8.5 and move through the constellations Piscis Austrinus, Capricorn, Aquarius, and Delphinus.

3122 Florence was discovered in 1981 by astronomer Schelte Bus from the Siding Spring Observatory in Australia. It has an orbital period of about 2.4 years with its distance from the Sun ranging from 1.0 to 2.5 astronomical units (one AU is the average Earth-Sun distance: 93 million miles or 150 million kilometers).

Asteroids pass close to Earth all the time. Earlier this year, a 10-foot (3-meter) wide NEO known as 2017 EA passed by at an altitude of just 9,000 miles (14,500 kilometers), well within the band of geostationary satellites at 22,300 miles (35,900 kilometers). It was detected just six hours before its closest approach.


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Christopher Paul has had a lifelong interest in spaceflight. He began writing about his interest in the Florida Tech Crimson. His primary areas of interest are in historical space systems and present and past planetary exploration missions. He lives in Kissimmee, Florida, and also enjoys cooking and photography. Paul saw his first Space Shuttle launch in 2005 when he moved to central Florida to attend classes at the Florida Institute of Technology, studying space science, and has closely followed the space program since. Paul is especially interested in the renewed effort to land crewed missions on the Moon and to establish a permanent human presence there. He has covered several launches from NASA's Kennedy Space Center and Cape Canaveral for space blogs before joining SpaceFlight Insider in mid-2017.

Reader Comments

Very interesting. I think I’m too tired from work to figure this out. Question: What is the projected speed of this object?

John, the speed is about 13.5 km/s.

13.5 km/s seems kind of slow

13.5 kms is about 8.37 miles per second which is about 30,132 mph. about normal speed for a rock just floating around in space

Not a concern…but worry about 2012 TC4 coming by Earth on 2017-Oct-12 at about 0.1 Lunar Distance, at a velocity of 7.6 km/s, size is about 16 meter diameter…

Kafir, I just looked it up, and while they say its going to pass about 30,000 miles away, they say they are sure it wont be closer than 4,200 miles. The size of the error factor makes me wonder….

Yup, just saying something we should watch…because of the error factor…makes for a great opportunity to observe.

I’m not giving ya the answer.

Go to bed and get some rest, …you’ll enjoy the process of figuring it out for yourself.

July 17, 2017 (partial message from Virgin Mary)

Beloved children of My Immaculate Heart, the earth shakes from one cardinal point to another.

Volcanoes quicken their activity due to the influence of a celestial body that is approaching Earth.




From where on earth will we be able to see it and at what time?

Thank you

How can I find this sucker with my telescope? What magnification?

Well, how to find it depends on when you want to look. Passing relatively close by, it will have a pretty quick apparent motion across the sky. It also won’t be naked-eye visible, so you can’t just look for it and aim the scope at it. Try NASA’s NEO website, that might be able to give you a location for the exact time you plan to see it. As for magnification, lower is better. Lower magnification gives you a wider field of view, so you can both get the scope on it easier and keep it in view with less fussing once you find it. No matter what magnification you use, it will only be a point of light anyway, so there’s really no purpose in jacking up the magnification.

Sorry, I missed typed my last name. The S is supposed to be a W.

Aquarius, not Acquirers. Sheesh.

American Patriot

Please land on CNN Headquarters!

I’ll try again! We had a near hit Nov.17th 2015, approximately 1:05AM. It was to big to miss yet I’m the only one to see it? Does anyone here save their photo’s of the sky? I’ve emailed NASA and several observatories with only 2 responses. This was huge, a mile or more in diameter and just hit the outer atmosphere enough to become visible. Here’s the report: The DEW line would had to have seen this at least. I expected the news to say WOW, near miss!!!, but nothing! Does that mean it will make another pass or hit in the future? Looks like it to me. I need a contact that has photographs of the sky from that time. BTW, it was close enough to see the large crater that covered most of it and some small craters on the back edge. Two nice concentric shock waves on the front, second one being the edge of the large crater. Can someone please respond to this to make sure it was posted? I’ve done this many times now with no acknowledgement, not sure it’s going anywhere. Thanks.

This isn’t the one I am watching. There is a smaller one that will pass by at about 27,000 miles (Within 3,00 to 4,00 miles of our geo stationary satellites) in October. This is only the second time it will have passed by earth that we know of after being discovered as it passed by at a much farther distance about 5 years ago. Initially we were told it could pass by as far away as 100,000 miles, then it as revised down to 27,000 miles? That is a very close call and one must wonder about the margin for error given that this is only its second recorded and observed pass. It is large enough that if it were to enter the atmosphere and explode aloft it would be roughly equivalent to the 1908 Siberia blast. If that were to happen over a populated area a lot of people would have a very bad day. If it were to actually impact….I do not believe we have any guide to work with.

Yes, that is 2012 TC4, coming by Earth on 2017-Oct-12 at about 0.1 Lunar Distance, at a velocity of 7.6 km/s, size is about 16 meter diameter…

16 meters, more that 50 feet in diameter, larger that a school bus, if it struck the Earth, would be a blast about 60 times larger that the blast at Hiroshima. While probably not an ELE, it would mesh up the climate in general, and nearer the impact site, would be devastation…

Noel Rodriguez

Could a close enough pass or a swoosh by a big enough rock say 50 miles in diameter be a factor on the surface of our planet

Maybe we should worry about the catastrophic Climate Changes that would occur if we are struck by even a relatively small asteroid. Statistically , sooner or later this will happen and NASA/NOAA should be developing means of detecting and deflecting those objects that could collide with us. This is basic common sense but there is a shortage of this in our government bureaucracies.

Face it, Folks. Sooner or later a big one will head this way with our number on it, and BOOM!!! There will not be a single thing that we can do about it.

You mean we can’t fly to the object and destroy it with nuclear weapons like in the movies?

DDaniel Josephdaniel Joseph

WE can only wait for “The Big One”, not IF but WHEN… In the mean time, hitting anything approaching Earth with an explosive of any kind, designed to shatter it, will only turn it from one big bullet to a shotgun – we’d still get hit but in more places. There is no easy answer unless it can be ‘redirected’ which isn’t in the cards yet.

Has NASA indicated any asteroids that they calculate will strike earth or be close enough to cause damage on earth?

This and the solar eclipse should be sufficient warning that we need to do something about global warming.

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