back to article Asteroid nearly gave Earth a new feature, two days after its discovery

On Saturday, the Catalina Sky Survey spotted a near-Earth asteroid of respectable heft – and today, it passed between us and the Moon. 2017 AG13 (the Minor Planet Center, MPC, entry is here) is about the size of a 10-storey building. Its velocity to Earth is 11 kilometres per second. It passed at 0.53 Lunar distance, or 203, …

  1. redpawn Silver badge

    Glad it missed

    Unfortunately the diagram missed too. Wouldn't want to keep the same scale for any of the parts or show the path it is taking through the Earth Moon system. Despite the diagram, thanks for the great work and interesting find.

  2. BugabooSue
    Mushroom

    "2017 AG13 is fairly dim, which made it hard to spot until it was quite close"

    Makes you wonder just how many we miss seeing altogether...?

    1. Anonymous Coward
      Devil

      You might not want to know. But at least the ones we miss will only be city wreckers and not plate busters. With those we'd have plenty of time to panic.

      1. Anonymous Custard Silver badge
        Mushroom

        I guess it depends on which city you happened to be in at the time...

        1. DropBear

          Then again, with a 2-day warning, you'd certainly be in wrong city if it managed to hit you...

      2. Alan Brown Silver badge

        "You might not want to know"

        Mostly we see them _after_ they've gone past.

        This has a lot more to do with them coming from the direction of the sun (lit from behind, so virtually impossible to see) and being lit up as they go past us than their dimness.

        The moon is about as black as a piece of coal. Most of these rocks are somewhat duller than that.

        1. Anonymous Coward
          Anonymous Coward

          "The moon is about as black as a piece of coal"

          source?

          The surface of the moon is mostly described as light grey. The moon's albedo is ~0.1 whereas coal has a much lower value ~0.05.

          If you are comparing snow, coal and the moon maybe you could say "the moon is about as black as coal" but without context I think your statement would be misleading for most people.

    2. Anonymous Coward
      Anonymous Coward

      "2017 AG13 is fairly dim, which made it hard to spot until it was quite close"

      Can we name it Katie Hopkins then? Please?

      :)

    3. Anonymous Coward
      Anonymous Coward

      All but the..

      final one.

  3. Brian Miller

    What if it had hit?

    No possible impact site mentioned! Gee, it would have been interesting to find out where it might have hit. Which is safer: northern or southern hemisphere? Which city should be buying asteroid insurance?

    1. seven of five

      Re: What if it had hit?

      If I remember correctly, Buenos Aires was the first city the bugs took out. At least in the movie...

      1. Anonymous Coward
        Anonymous Coward

        Re: What if it had hit?

        My family is from Buenos Aires and I say 'kill them all '

      2. Voland's right hand Silver badge

        Re: What if it had hit?

        At least in the movie...

        If memory serves me right, the book while not openly stating it as the first implies it was the first hit.

      3. Anonymous Coward
        Anonymous Coward

        Re: What if it had hit?

        It was a movie?

        1. Anonymous Coward
          Anonymous Coward

          Re: What if it had hit?

          It was a movie?

          Yes, with a tenuous connection to the novel by Robert Heinlein. Read the novel instead.

    2. David Knapman

      Re: What if it had hit?

      Because if you're going to apply an adjustment to its trajectory, such that instead of missing the planet it hits, the possible impact point is... anywhere.

      1. John Robson Silver badge

        Re: What if it had hit?

        To be fair you could probably specify a hemisphere...

        I mean - one side of the earth was facing in the direction from which the asteroid came at the time it passed by - so I reckon that hemisphere was more 'at risk' than the other...

        But yes - it's like asking which section of a tennis court the basket ball would land in if bowled from between the posts on a rugby pitch.

    3. Grikath

      Re: What if it had hit?

      Íf it'd had hit Earth's atmosphere it would most likely not have hit at all.

      Note the comparison to the Chelyabinsk rock... At that size meteors don't burn up, but disintegrate/explode midair.

      It's what you get with Youth.. Not patient enough to wait until they touch down and make a nice crater.. Noooo.... They have to do the whole "You don't need Nukes to make a Big Bang" right away.. **

      ** No... I deny any science here... This is the celestial Youf , Showing Off , playing chicken with the older bigger kids, and occasionally failing to miss.

      1. Richard 12 Silver badge

        Re: What if it had hit?

        Could still seriously damage a small town.

        Most likely to hit the sea of course.

      2. Alan Brown Silver badge

        Re: What if it had hit?

        "At that size meteors don't burn up, but disintegrate/explode midair."

        If the angle is shallow, yes.

        Chebalinsk skimmed through the atmosphere for several hundred miles before breaking up.

        On a steeper angle the airburst can bring a supersonic shockwave of superheated air to the ground.

        if you have a lot of rocks, this can result in a very bad day (hot enough to melt surface rocks, resulting in a volcanic appearance without any nearby vulcanism - and there are a few places on the planet like this) - one researcher by the handle of craterhunter has been advocating this as a possible cause for the sudden extinction of north american megafauna and the younger dryas periods. Some of the supporting evidence is quite compelling, in particular "recently" melted surface rocks in southern North America with no supporting igneous activity.

        1. Anonymous Coward
          Anonymous Coward

          Re: What if it had hit?

          I looked at craterhunter's site, and I can say as a Google Earth monster that the 'crater' image he has on that page does appear to the untrained eye to be a blast site, but in fact is typical desert erosion that just happens to be arranged to look kinda radial in pattern.

          Of course, I did have to find the site on Google Earth to be sure, and craterhunter neglected to provide a link or info. And it does look like his photos are a bit doctored to make the 'crater' stand out a lot. I've spent many years living and hiking on just such terrains. They're everywhere in the US Southwest, and that site shows a caprock layer around the edge of a bowl with erosion proceeding into the soft layers below the caprock. It's extremely typical of the desert here.

          In short, cool as it sounds, I was not impressed with the "ancient airbursts killed the megafauna" theory based on that proposed location. Don't have much to say about other evidence, but I'd guess he's a bit of a kook. A fun one tho!

        2. This post has been deleted by its author

          1. Sir Runcible Spoon

            Re: What if it had hit?

            Younger Dryas period - isn't that when Atlantis was sunk?

            1. Anonymous Coward
              Anonymous Coward

              Re: What if it had hit?

              I thought it blew up...?

              1. This post has been deleted by its author

              2. Real Ale is Best
                Joke

                Re: What if it had hit?

                I thought it blew up...?

                No, it caught fire, fell over, and then sunk into the swamp.

  4. Your alien overlord - fear me

    So, how big was the asteroid in koala bears?

    1. Sir Runcible Spoon

      Yeah, and what was the speed on the 'sheep in a vacuum' scale?

  5. Florida1920

    Biggest fish fry in history

    If it hit an ocean.

    1. Trevor_Pott Gold badge

      Re: Biggest fish fry in history

      Pfffffft. Not even close.

  6. This post has been deleted by its author

  7. Winkypop Silver badge
    Mushroom

    One of these days...

    POW!!! Right in the kisser!"

    1. Anonymous Coward
      Anonymous Coward

      Re: One of these days...

      All right Ralph, if the Earth had a kisser, where would it be?

      1. John Brown (no body) Silver badge
        Coat

        Re: One of these days...

        "All right Ralph, if the Earth had a kisser, where would it be?"

        France. At least that's what they claim.

        1. Sir Runcible Spoon
          Joke

          Re: One of these days...

          I don't know where the intake aperture would be, but I could make some educated guesses on the output vent!!

    2. Anonymous Coward
      Anonymous Coward

      Re: One of these days...

      Great, now you've just awoken a dozen Russian sleeper agents.

  8. FozzyBear

    We still have Bruce Willis and team on standby, right?

    1. Anonymous Coward
      Anonymous Coward

      No, Bruce can't help us now. Getting kinda long in the tooth. We need new heroes, men and women (and others) who will place their fragile bodies on the line for their planet. 'Git 'er done' types (like Bruce) who don't flinch when flipping the Nuke Gun lever to 'Auto.'

      Um, is Chuck Norris still available...?

      1. Anonymous Coward
        Coat

        The asteroid belt wasn't created by God, it was created when Chuck Norris got mad and roundhouse kicked a planet.

      2. TheProf Silver badge

        Dang!

        "Um, is Chuck Norris still available...?"

        I had to check: Chuck is 76 while Bruce is still only a nipper at 61.

        1. Anonymous Custard Silver badge
          Headmaster

          Re: Dang!

          The question is which would take longer to get ready for action - either of those two or the space shuttle to take them up there?

        2. Alan Brown Silver badge

          Re: Dang!

          Dolph Lundgren is available - and he actually has a chemistry degree under his belt too (studied at MIT).

          1. Sir Runcible Spoon

            Re: Dang!

            These days he looks like he face-washes in his chemistry experiments.

    2. Voland's right hand Silver badge

      I'd rather stick with Robert Duval and Mary McCormack

      At least they had the right attitude: " Well, look on the bright side. We'll all have high schools named after us. "

  9. Anonymous Coward
    Anonymous Coward

    Fairy Dim and hard to spot?

    A bit like most politicians debating the NHS crisis in Westminster.

  10. Neil Barnes Silver badge
    Boffin

    So close?

    I'd best take my hat off, then.

    btw - doesn't 'velocity' include a direction, not just a speed? And surely the quoted 11km/s isn't a constant differential? Just askin'...

    1. mr.K

      Re: So close?

      In science velocity is a vector and thus including a direction. However according to the dictionary it can simply mean speed. So I think it is one of these instances where a field of study has taken two words that mean the same and added a distinction that wasn't there, before they go out and pester people that actually use it correctly. (I don't actually know the historical development of this word though)

    2. Methusalah

      Re: So close?

      I think vector is the one with the directional component. Though my memory is a little fuzzy these days

    3. phuzz Silver badge
      Boffin

      Re: So close?

      Yep, in physics velocity is a vector and so always includes a direction, as well as a speed.

      However, in general English, velocity and speed mean the same thing.

      1. DropBear

        Re: So close?

        Interesting. The distinction felt artificial to me, then I just realized neither of the other two languages I speak (one of latin origin, one not) has different words to designate speed vs. velocity. Sure, there are a bunch of more or less synonyms, but as far as physical properties are being described, both have only one word for both the scalar and the vector...

    4. Peter Gathercole Silver badge

      Re: So close? Re:Vector

      If I remember my A-Level and university maths, what a vector represents is dependent on the number of dimensions you're working in.

      If you are working in one dimension, a vector and a scalar are the same thing. In two dimensions (the standard environment when you are learning vectors IIRC), a vector is normally described as a one by two array in a cartesian co-ordinate system, or a scalar and an angle in a polar co-ordinate system.

      In three dimensions, a vector will be a one by three three array in cartesian, or a scalar and two angles in polar co-ordinate system.

      I'm sure that some theoretical physicist or mathematician will point out that they work in more than three dimensions!

      So the upshot of this is that if you are working in one dimension, taking the path of the asteroid as a dimensional frame of reference, the velocity, even if treating it as a vector can be considered the same as it's speed, and this is what most lay people will count as a velocity.

      Of course, celestial mechanics is never that simple, and is normally in at least 4 dimensions.

      1. Daniel 18

        Re: So close? Re:Vector

        Ummm.... no.

        A scalar is dimensionless.

        A vector has dimension(s), and is expressed with respect to a co-ordinate system or systems, as it has a direction as well as a magnitude. It can be represented as an ordered n-tuple, which itself has one dimension, where n is the number of dimensions represented by the co-ordinate system.

        1. Anonymous Coward
          Anonymous Coward

          Re: So close? Re:Vector

          In common English, I would say that speed has an "absolute" quality to it; even though speed/velocity can never be truly absolute, people have a notion of a stationary position and therefore an absolute speed.

          Saying "it's speed relative to Earth" is fine, but just doesn't sound quite right. "It's velocity relative to Earth" is much better.

          1. Tom 7 Silver badge

            Re: So close? Re:Vector

            But what is this bollocks the US police force use: "Rate of speed" as in '"he was travelling at a great rate of speed"? Acceleration? Travelling in quantum ways so having lots of different speeds?

  11. Chris G Silver badge

    The Force

    I felt it in the Force, it was an Imperial ship looking for rebels who thought they could hide on a backwater planet.

  12. Merlinski
    Mushroom

    IIRC from the Bruce Willis documentary, these little rocks precede the really big rock by a couple of days ...

  13. Death_Ninja

    No El Reg SI units in this article?

    How far away was the asteroid? In Nelson's Columns or Olympic Sized Swimming pools...

    Was the asteroid bigger than a London Double Decker bus or just the size of a Shetland Pony.

    I demand proper measurements!

    1. Richard 12 Silver badge

      Re: No El Reg SI units in this article?

      One to three doubledecker buses.

      As to how far away, I'd say "just far enough"

  14. David Nash
    Mushroom

    not to scale

    The picture makes it look much worse than it actually was. For those who can't be bothered to read the text, that is.

    1. DropBear
      Trollface

      Re: not to scale

      Quite. It's common knowledge the only thing we really need to fear (well, beside "fear itself") are high-altitude Nokias...

  15. Anonymous Coward
    Anonymous Coward

    Who's Piloting this Planet

    Whoever it is that's piloting this planet may get demoted over this near miss.

    What? Oh. Well, shouldn't someone be at the controls? It's not like the planet has an auto-pilot.

    1. Gobhicks

      Re: Who's Piloting this Planet

      Attention technicians of Spaceship Earth. This is your captain speaking. Your captain is dead.

      1. John Brown (no body) Silver badge
        Joke

        Re: Who's Piloting this Planet

        "Attention technicians of Spaceship Earth. This is your captain speaking. Your captain is dead."

        Is that a side effect of the botox and orange hair?

  16. DCFusor
    Joke

    My fault

    I voted "giant meteor" in the last election. Evidently, there is a recount being attempted.

    1. mosw

      Re: My fault

      Looks like the "dim asteroid" still won.

    2. Anonymous Coward
      Anonymous Coward

      Re: My fault

      > "I voted "giant meteor" in the last election."

      That'll go nowhere fast. We need to organize the Giant Meteor Party!

  17. Anonymous Coward
    Anonymous Coward

    Asteroid FMTWC2017 first seen heading away

    F* me that was close

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