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Near Earth Asteroid 'Florence' Makes a Close Pass (space.com) 105

kbahey writes: A big, bright, near-Earth asteroid, known as 3122 Florence, made a safe fly by Friday night. Florence is classified as a Potentially Hazardous Object. At its closest, it was about 7 million km (4.4 million miles) away from earth. It is still visible in amateur telescopes over the next few days where it would be seen to move over several minutes against the background stars. It can be located using this map. According to NASA officials, the asteroid hasn't been this close to Earth since 1890, and it won't be this close again until 2500. "Asteroid 3122 Florence was discovered in 1981 by astronomer Schelte 'Bobby' Bus at the Siding Spring Observatory in Australia," reports Space.com. "The asteroid is named in honor of Florence Nightingale (1820-1910), who pioneered modern nursing, NASA officials said in a separate statement."
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Near Earth Asteroid 'Florence' Makes a Close Pass

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  • Congratulations!

    This, at least sounds like news for nerds although I understand that motto is gone.

    Thank you,

    • by Nutria ( 679911 )

      While "550 Earth diameters" is nerdy, it's 550 Earth diameters away!!!!

      Only a ninny bureaucrat with too much time on her hands would classify that as "potentially hazardous".

      • Is that centre to centre or surface to surface?

      • it's 550 Earth diameters away!!!! Only a ninny bureaucrat with too much time on her hands would classify that as "potentially hazardous".

        The phrase "potentially hazardous" does not mean that it will be hazardous on this particular pass. It means that it is in a orbit that makes repeated close passes near Earth, so it potentially may be hazardous on a future pass.

        • by Nutria ( 679911 )

          the asteroid hasn't been this close to Earth since 1890, and it won't be this close again until 2500.

          How much closer will it be 483 years from now? We've got a lot more shit to worry about than this...

          • The phrase "potentially hazardous" does not mean that it will be hazardous on this particular pass. It means that it is in a orbit that makes repeated close passes near Earth, so it potentially may be hazardous on a future pass.

            the asteroid hasn't been this close to Earth since 1890, and it won't be this close again until 2500. How much closer will it be 483 years from now? We've got a lot more shit to worry about than this...

            That's the definition of the word. The word is not defined as "objects to panic about right now."

            If you don't want to worry about a potentially hazardous object, you don't have to. That does not mean it is not potentially hazardous. It just means you're not worrying about it.

            More detailed definition here: https://cneos.jpl.nasa.gov/about/neo_groups.html [nasa.gov]

            • by Nutria ( 679911 )

              0.05 au sounds close, and -- astronomically -- it is. But then, Alpha Centauri is relatively close to Earth, compared to the Andromeda galaxy.

              Also, why an absolute magnitude of 22.0 or greater? What about the big, dark iron asteroid with an H of 23 who's MOID is 10^-5 au?

              • Also, why an absolute magnitude of 22.0 or greater? What about the big, dark iron asteroid with an H of 23 who's MOID is 10^-5 au?

                Because absolute magnitudes can be measured as soon as an asteroid is found, when an asteroid is far away, while what an asteroid is made of, and what its color is, cannot.

                • Because absolute magnitudes can be measured as soon as an asteroid is found,

                  Weeeeellll ... for certain values of "found", you could make that claim. If you've observed an object for long enough to work out it's orbit, and found a "pre-covery" image somewhere so that you've got the multiple-position data needed to calculate an orbit to MPC standards, then yes, you have the distance data needed to convert the apparent magnitude measured at your telescope into an absolute magnitude as it would have at a range

                  • We don't really consider an asteroid "found" until there are more two observations; otherwise you don't where it is.

                    However measuring it's colour (a hint to composition) and taking a reflection spectrum (a better hint to composition and classification) can theoretically take place in the first observation run (if your imager system can switch between imaging and spectroscopy without significant reconstruction).

                    "theoretically" maybe. Practically: no. You simply need a lot more photons to do spectroscopy than you need to just see something is there. You can only get spectra from astwroids that are reasonably bright, which, for asteroids this tiny, means reasonably close.

                    • Which is why colour estimation is easier to do than spectroscopy, though it provides less information. So your observing log looks like:

                      (previous observations)

                      Found something serendipitously in target field that's not in DSS/ 2MASS/ SIMBAD - looks like it may be an asteroid. 10 shots for positional measurement - first 3 in full bandwidth, 3 with B filter, 3 with V filter, check shot. Use exposure-doubling protocol if filtered views below detection limit.

                      (continue planned observing run)

                      [Next night] Conti

  • An asteroid buzzed the Earth at 50,000 miles away last year.

    https://www.space.com/33891-newfound-asteroid-buzzes-earth-2016-qa2.html [space.com]

    • by ls671 ( 1122017 )

      I might have read your link too quickly but anyway; what strikes me in those kind of reports is that they don't mention the relative speed of the object with Earth as a reference and this plays a big role in the amount of energy released should an impact occur.

      • When you get hit by a bus it doesn't really matter if it's going at 250 km/h or 2500 km/h.

        • Re:That's nothing... (Score:5, Informative)

          by rgbatduke ( 1231380 ) <rgb@phy[ ]ke.edu ['.du' in gap]> on Monday September 04, 2017 @08:40AM (#55136289) Homepage

          Asteroids will hit the Earth (if at all) at LEAST at 11.2 km/sec, as they have greater than escape energy relative to the Earth's gravitational field. That's 11.2 kilometers per SECOND, or a bit over 40,000 kilometers per HOUR. The energy released is greater than 64 million joules per kilogram of rock (escape energy). So if you take a (say) 2.5 km ball of rock (5 km in diameter), roughly estimate its mass as 4 times r^3 you get 4 e+18 joules. Convert this to tons of TNT and you get roughly a teraton. The total explosive energy of the entire nuclear arsenal of the Earth is less than 7 gigatons (including reserve weapons -- only around 1 GT is on delivery vehicles almost all of this belonging to the US and Russia). The biggest explosion in recorded history was the explosion of Tambora in 1815, estimated at 33 GT. This is then equivalent in crude terms to over 100 times the entire global arsenal nuclear and conventional, or over 30 times the explosive power of the largest explosion in recorded history, one that altered global climate for close to a decade. Or GREATER.

          I'm not sure "hit by a bus" is an apropos metaphor.

          • isn't escape velocity relative to distance though? Since gravity is greater in proximity, it would follow that something 4.4 million miles away doesn't need the speed that something 25,000 miles away would need.

            Actually a serious question, I don't know.
            • So here's a serious answer. Gravitational potential energy has the form U = -GMm/r where r is the distance from the center of the earth. Practically speaking, this means that a kilogram of mass sitting on the surface of the Earth has a gravitational potential energy of -GMm/R where R is the radius of the earth and m = 1. If you work out the arithmetic, this is NEGATIVE 64 MJ give or take a hair (GM/R = gR = 6.4x10^7 J).

              Total energy is potential energy plus kinetic energy: E = K + U with K = 1/2 mv^2. I

            • You are (I think) confused and have this backwards. We consider how much energy/speed we have to give something to throw it up to arrive, at rest, at a maximum height of e.g. 25,000 miles (which is the energy/speed it will have if it lands when dropped from there, at rest. To throw it up HIGHER you have to throw it FASTER with MORE energy. Gravitational POTENTIAL ENERGY is actually LESS in proximity -- greater in magnitude but (by convention) MORE NEGATIVE.

              Specifically, if we drop one kilogram from rest

          • Escape velocity is relevant for launching somthing into orbit, or to escape to outer space. Hence the name.
            It has nothing to do at all with the potential speed of an impacting body!

            • You are mistaken. Escape velocity has nothing to do with launching something into orbit. Well, yes it does. One has to add half of escape energy to an object as kinetic energy to establish it in a low, circular orbit, but that is more or less an interesting algebraic coincidence (related to the virial theorem). Furthermore, as I work out algebraically above, escape speed IS EXACTLY the speed of an object with escape energy, and is in turn BY DEFINITION the speed of an object dropped from infinitely far

              • and is in turn BY DEFINITION the speed of an object dropped from infinitely far away, initially at rest.
                It isn't.
                An asteroid can hit earth with any imaginable speed. And usually that is far faster than escape velocity.
                No idea why you as self proclaimed physics teacher does not know that, facepalm.

                So go find one of your own, or google "escape velocity" or "escape speed".
                Why should I google trivialities?

                But as you insist, to make a fool out yourself:
                a) Escape velocity earth: 11.2 km/s
                b) earth orbit speed:

                • So, you didn't bother to read any of the other two or three posts where I worked out the algebra (face-palm) before spouting crap. No, asteroids cannot hit "at any speed imaginable". They can hit at any speed that is GREATER THAN OR EQUAL TO Earth's escape speed, as I actually discussed and derived. Also, escape speed FROM EARTH is relative TO EARTH. So yes, I absolutely neglected solar potential energy because it just doesn't vary that much across the range where most of the actual acceleration of an

                • You and RGBatDUKE are talking at cross purposes.

                  You :

                  a) Escape velocity earth: 11.2 km/s
                  b) earth orbit speed: 30km/s
                  c) incoming asteroids speed: what ever you want. If it is e.g. "your escape velocity" and it comes retrograde into the earth, then it is 41 km/s

                  Which is a different situation to RGB's :

                  escape speed IS EXACTLY the speed of an object with escape energy, and is in turn BY DEFINITION the speed of an object dropped from infinitely far away, initially at rest

                  Of course, if you complexify RGB's tex

              • by Trogre ( 513942 )

                So, Earth's atmosphere doesn't slow asteroids down, and therefore the minimum speed of an asteroid falling unimpeded from space is also the minimum speed needed to sling something back into space?

                Is that what you're saying?

                • "Earth" slows asteroids down when they land on it. To rest, in the Earth's rest frame, in reasonable approximation. This is a completely inelastic collision, and given the disparity in their masses nearly all of the asteroid's relative kinetic energy is transformed into heat. Some of that heat heats the atmosphere as the atmosphere lands, sure, but seriously, look at the magnitudes involved. This is pretty much irrelevant, given that the impact is going to blow the friction-heated atmosphere near the im

                • So, Earth's atmosphere doesn't slow asteroids down

                  Not significantly. (Please note the word "significantly" in the phrase "not significantly".) The atmosphere is about 10km thick for the bottom half of it (by weight), which is traversed by an impactor in 0.9 seconds or less (see dispute surrounding ; rgbatduke is right). Even for something as small as a bullet, 0.9 seconds of atmospheric drag isn't sufficient to make them safe.

                  For something like the Chixulub impactor (the so-called "dinosaur killer" ; see m

          • Why is escape velocity relevant? Are we chucking the bloody things into space? I was under the impression that they're moving the other way...

            And this got to +4 informative?

            • by ColaMan ( 37550 )

              Escape velocity is the minimum velocity you need to completely escape Earth's pull. So if you you're on the Earth's surface, and you impart a velocity of 11km/s to an object, it will juuuuuuuust escape Earth's sphere of influence.

              Similarly if you have an object in space that is juuuuuust within Earth's sphere of influence and it gets pulled in, it will have a velocity of at least 11km/s by the time it reaches the surface.

              "At least" being the operative term there, because the object could already be heading

            • Read rgbatduke's comments. He's right.
          • I guess amend that to "hit by a bus when you are a fly" ?
      • Not only that but the MASS of the object is also important. Little rocks or grains of sand hit our atmosphere all the time going thousands of miles per hour (we call them shooting stars). I think it has to be about the size of a basketball before it has a chance of actually striking the ground before burning up.
        • by ls671 ( 1122017 )

          The mass is important but with a big enough mass, the speed becomes much more important since the kinetic energy varies to the square of the speed:
          E = 0.5*m*v*v

          • with a big enough mass, the speed becomes much more important

            Why does the relative importance change? Is there some slider control that trades one for the other?

            • by ls671 ( 1122017 )

              As another poster has mentioned, small enough objects don't make it to the Earth surface due to the protection of the atmosphere. I assume they just disintegrate faster the greater the speed.

              Also, to further illustrate the formula I posted, if the mass is 8 times greater you get 8 times more energy but if the relative speed to Earth is 8 times greater you get 64 times more energy and it is even more than that if the object travels at a considerable fraction of the speed of light relative to Earth. The formu

  • If this asteroid is classified as a "Potentially Hazardous Object", then why is it being reported two days *AFTER* the pass?
    • by ls671 ( 1122017 )

      Because we didn't want to cause mass panic. This is how things works out most of the time.

    • by lucm ( 889690 )

      Probably because most of the people who care were busy taking ecstasy at Burning Man

    • by Anonymous Coward

      Too dangerous.

      Imagine the TFA-oid were still inbound.
      Some idiot post article on /.
      Suddenly it gets slashdotted.
      Asteroid becomes laggy and stops mid-space.
      Not only would a laggy/frozen asteroid annoy the astronomy community world-wide but it would also slowly start moving right towards earth - being pulled in by our gravity.

      Solution is simple: wait until it passed, most people will ignore asteroids that aren't inbound.

    • If this asteroid is classified as a "Potentially Hazardous Object", then why is it being reported two days *AFTER* the pass?

      it is a potentially hazardous object because it is in a orbit that makes repeated close passes near Earth, and therefore it may intersect the Earth's orbit at some time in the future (beyond the time frame in which we can make exact predictions, due to chaos). It is potentially hazardous.

    • Which part of:
      4
      million
      miles
      away

      did you not get?

      I can easily translate that into kilo meters for you, if that helps. (You have a rough idea how far away the moon is, yes? Why do I have the feeling that you have no clue ... ? )

  • So glad.. (Score:4, Funny)

    by Anonymous Coward on Monday September 04, 2017 @12:56AM (#55135257)

    "A big, bright, near-Earth asteroid, known as 3122 Florence, made a safe fly by Friday night."
        So glad we didn't damage it. Those things can be expensive!

  • Let's honor a woman who saved many lives by naming a rock big enough to cause a mass extinction event after her!

    • Let's honor a woman who saved many lives by naming a rock big enough to cause a mass extinction event after her!

      Yep, that was my biggest takeaway from the summary, too. If we are driven to extinction, it should be by a rock named after something bad, like a Big Mac.

  • was my first thought.

  • And statistics... (Score:5, Informative)

    by jandersen ( 462034 ) on Monday September 04, 2017 @04:11AM (#55135641)

    The asteroid is named in honor of Florence Nightingale (1820-1910), who pioneered modern nursing

    Indeed, Nightingale is described as "a true pioneer in the graphical representation of statistics", and is credited with developing a form of the pie chart now known as the polar area diagram,[53] or occasionally the Nightingale rose diagram...

    • Presumably, science and math is how you pioneer *modern* anything, nursing certainly not excluded?
      • Indeed. For some reason, part of my comment went missing - I quoted a bit from the previous post, then added my comment (which disappeared for some reason), then quoted a bit from wikipedia, which now shows up as the unquoted part. As for Mrs Nightingale's contributions to nursing, I think mathematics and scince were only minor contributions; far more important were things like hygiene, nutrition and simply being organised and prepared before the event, to take care of the wounded with trained nurses rather

  • The moon is 384K km away. This was over 20x further away.

    I wish we had been warned. Then I could have spent lots of time not worrying about it in the least.

  • Here are two composite photos showing the asteroid moving against the background stars: Florence 1 [astrob.in] and Florence 2 [astrob.in].

  • by Anonymous Coward

    So, a "Potentially Hazardous Object" (Wikipedia says "3122 Florence" is possibly "large enough to create serious damage were it to impact") is named "in honor of Florence Nightingale (1820-1910), who pioneered modern nursing" (from NASA statement quoted in the summary).

    The idea of the asteroid version of the "Lady with the Lamp" (absolute magnitude H=22), making her rounds (every 859 days, with an eccentricity of 0.42), might one day *cause* millions of people to be killed or wounded, is simply begging the

  • I thought at first - surely there were a lot more than 3121 asteroids identified by 1981, but on checking, it's MPC number (essentially the sequence number of orbits reported to the Minor Planets Centre) is 21995, so by 1981 almost 22 thousand asteroids (etc) had been identified. Which sounds much more like I thought.

    For comparison, the current figures from the MPC are

    Minor Planets Discovered
    THIS MONTH: 21
    THIS YEAR: 19154
    ALL TIME: 734274

    So, on a monthly basis, we're acquiring data at a rate comparabl

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