Small asteroid to buzz Earth on May 28

By Phil Plait | May 25, 2012 11:33 am

Asteroid 2012 KP 24, a smallish rock about 25 meters (80 feet) across, will pass pretty close to the Earth on May 28, buzzing us at a distance of about 30,000 kilometers (18,000 miles) 51,000 kilometers (32,000 miles) [Note: the numbers at JPL have updated, making the pass a bit farther out than the numbers I originally used]. That’s close as passes go, but still a clean miss.

Closest approach is at about 15:00 UTC (11:00 a.m. Eastern US time) on May 28. It’ll actually pass Earth closer than our geosynchronous satellites! At closest approach, it’ll whiz by at about 13 km/sec (30,000 mph). I’ll note I calculated most of these numbers based on the JPL site linked above, and they may be refined over the next day or two [see?]. It was discovered by the Catalina Sky Survey (as so many near-Earth asteroids are) on the evening of May 23/24.

Let me stress, as always, that there is essentially zero chance of impact here. A miss like this is still miss, so don’t fret over what will no doubt be a slew of panicky doomsday sites and videos that will pop up about this rock — that happens every single time we get a near-Earth pass of an asteroid, and yet we’re still here! If we see one really and truly on its way to an impact, trust me, I’ll let you know.

And actually, things like this make me feel safer: we’re looking and finding these asteroids! The fact is there are a lot of eyes on the skies right now, scanning the heavens and looking for potential impactors. And note that the JPL page for this rock has all the relevant info there.

Tip o’ the Whipple shield to BABloggee Terry Hash. Image credit: ESA/Rosetta, NASA/NEAR – I photoshopped asteroid Mathilde onto an image of the Earth, so this is not KP24!

Related Posts:

A brief bit about asteroid 2012 DA14
No, asteroid 2012 DA14 will not hit us next year
Asteroid 2011 AG5: a football-stadium-sized rock to watch carefully
Updated movie of asteroid YU55, plus bonus SCIENCE
Asteroid 2007 TU24: No Danger to Earth

MORE ABOUT: Asteroid 2012 KP24

Comments (35)

  1. Chris

    …that there is essentially zero chance of impact here

    That “essentially” has me concerned 😛

  2. Chew

    Heh. The distance has already been updated to 57,000 km. Heh.

  3. Will

    Also, 25m doesn’t sound all that big. What kind of damage would we see if an asteroid that size *did* hit?

  4. Jo

    Thanks for the update :) I discovered the NASA link last night and the subsequent KP 24, but when I tried to google it today nothing comes up but ‘conspiracy theory’ sites! I was beginning to think I had imagined this new discovery :)

  5. Chip

    In the Hollywood movie script (based loosely on true events,) there is no chance of an Asteroid impact – until – “2012 KP 24” is deflected by an unforeseen discarded Russian third rocket stage from the 1960s. Incredibly, this alters the course for an impact at (plot twist No. 2) exactly the same location as Meteor Crater in Arizona, leading to (plot twist No. 3) an entrepreneur selling tickets to the “Crater Enlargement Event”. 😉

  6. If my math is right, this should be about mag 17.5. So this might be visible in a 16 inch (400 mm) scope visually. The time uncertainty (45+ minutes) is also problematic. Figuring out where to look from where you are is an exercise for the reader.

  7. Rob

    I know that 25 meters isn’t that big, and you didn’t say what kind of an asteroid it is, but (at the risk of feeding the doomsday-trolls) what kind of damage would this thing do if it were to hit? Burn up in the atmosphere for a light show? Wipe out a city? Burn to a little chunk that might punch a hole in someone’s couch?

  8. Pete Jackson

    @2 Chew: If the error in the original prediction was 27,000 km (30,000 to 57,000), then it was also possible for the error to have gone the other way (30,000 to 3,000). And passing the Earth’s center by only 3,000 km would have made a big splat since the radius of the Earth is almost 6,400 km!
    “Essentially zero chance of impact”: Harumph!

  9. Benjamin Franz

    > “And actually, things like this make me feel safer: we’re looking and finding these asteroids!”

    Well, yes. Finding them is good.

    But I would still feel a bit better if we were discovering these near approaches more than a few weeks before they are due…

  10. Chris

    @3 Will

    Surprisingly quite a bit, if it stayed together on impact. Assume it’s a sphere 25 m in diameter. That gives it a volume of 8200 m^3. Now assume a typical rock density of 2500 kg/m^3, That gives it a mass of 20 x 10^6 kg. Now it’s moving past us at 13 km/s. The kinetic energy would be (1/2 mv^2) = 1.7 x 10^15 Joules. This is about 0.4 megatons of TNT. So a decent sized nuclear bomb going off. The Tunguska event was estimated as 10-30 megatons.

    Fortunately if this was on a collision course, once it impacted the atmosphere it would break apart. While the energy delivered would be the same, it would be spread over a wider area helping to mitigate some of the damage. And also the odds of it hitting the ocean are much greater than hitting the land.

  11. Bearpaw

    When I plug numbers into Perdue’s Earth Impact Effects Program, it estimates that an asteroid that size would air-burst at about 10 miles up, “although large fragments may strike the surface.”

    So … loud bang, maybe some localized damage from the pieces. No biggie even if it didn’t miss Earth.

  12. Jim Shaver

    @3 Will: It would be very bad for you (and your neighborhood), if it happened to hit your house. I’d keep my eyes on the sky, just in case.

  13. Bill K

    Purdue University has a web site at:

    that allows you to calculate the impact effects of asteroids.

  14. Polo

    @3 Will & @6 Rob: I checked a couple of sites (one was ) that calculate impact craters based on basic parameters, and apparently it greatly depends on the asteroid’s density.

    Using a “dense rock” parameter of 30oo kg/m^3 it shows that no crater would be left, but that an asteroid with an iron density of 8000 kg/m^3 would leave a 125m deep and 600m wide crater…

  15. Jiminy

    I’ve done the math and checked some online sources.

    IF a 25M rock was to hit, it seems almost certain the amount of damage would be on the scale of Lindsay Lohan. Not too bad, mostly just a lot of noise while obliterating its career.

    Just kidding. I have no idea.

  16. That was just warning shot…

    …Next time we will aim to hit!

  17. Chip

    Can it be calculated how its orbit would be perturbed after coming close to the Earth?

  18. VIP

    What would happen if a similar rock was aiming to hit earth? Do we have any nuclear facilities to break it up, or are all our nuclear capabilities based on destroying humans?

  19. This could be viewed as an oportunity. A “practice” round if you will. Target practice/ capture/ re-direction/ hitching a ride/ exploding it after passing earth for analysis/ ect. :)

  20. Chris

    @18 VIP

    Unless we have some super secret launch capability, all our nuclear missiles are Earth bound. They wouldn’t want to nuke the asteroid just outside the atmosphere since that would probably create more damage than letting it hit. The electromagnetic pulse and debris would knock out a good percentage of the satellites. Also it’s not trivial to make a rocket leave near Earth orbit.

  21. Hemo_jr

    If it hit my house, I could probably get more for it than the damage it caused. All in all, I’d prefer it hit the back yard.

  22. R3alist1

    So….why do we look for them if we don’t have anything in place to remove the threat again? I must’ve missed that memo…..

  23. Naomi

    I know it’s no longer in range of geosynchronous satellites, but out of curiosity, is there any chance that another NEO in the future could take one out? I realise that it’d be a hell of an unlikely shot (satellites aren’t exactly big targets!), but they are hanging out in roughly the same vicinity, so it’s not impossible, right?

  24. Image credit: ESA/Rosetta, NASA/NEAR – I photoshopped asteroid Mathilde onto an image of the Earth, so this is not KP24!

    Is there any particular reason why you chose Mathilde to stand in for 2012 KP 24 instead of, say asteroid Itokawa or asteroid Eros or asteroid Annefrank, BA?

    (See images of all the asteroids and comets humans have visited except for Vesta and Comet Grigg–Skjellerup – visited by Giotto in 1992 but no photos taken of it due to the camera being destroyed – linked to my name.)

  25. #22 @R3alist1: “So….why do we look for them if we don’t have anything in place to remove the threat again? I must’ve missed that memo…..”

    Mostly for scientific reasons. “Planetary defence” is just a nice bonus.

    However, even knowing a few days or even hours in advance of an actual impact could be valuable. For a small object like this it would be of scientific interest to observe the impact and to go look for fragments.

    For something a bit larger warning people could make a big difference to casualties: evacuation of a direct impact zone might be possible and there’d a large area around the impact where simply taking cover, boarding up windows and that sort of thing would help a lot. An ocean impact causing a tsunami would be easy to mitigate by evacuations of low areas around the basin in question, shutting down nuclear reactors, and so on.

    Also, a relatively small impact in an area of the globe where tensions are already high could lead indirectly to catastrophic consequences which could be averted by prior information. E..g., suppose there had been unexpected new crater in Israel or Iran a while ago – would there not have been a severe risk of “retaliation”?

    The cost of the surveys is, in the grand scheme of things, tiny and the combination of scientific information and the potential for warning makes them well worthwhile.

    Development of technology to deflect or destroy the asteroid would be more double edged because of the risk of abuse. Also, it’d be a lot more expensive.

  26. Peter B

    Naomi @ #24 asked: “I know it’s no longer in range of geosynchronous satellites, but out of curiosity, is there any chance that another NEO in the future could take one out? I realise that it’d be a hell of an unlikely shot (satellites aren’t exactly big targets!), but they are hanging out in roughly the same vicinity, so it’s not impossible, right?”

    Absolutely a collision between a satellite and an asteroid would be possible. For all we know, it’s already happened: there are a lot more small rocks Out There than large ones. A rock the size of your fist would still destroy a satellite, but would be essentially undetectable Down Here. So I’d suggest it’s possible (although spectacularly unlikely) that any satellite which suddenly exploded could have been the victim of such a hit as you asked about.

    Having said that, the thing to keep in mind that geosynchronous satellites orbit directly above the Earth’s equator. That narrows down the target area a lot. Rocks orbiting the Sun could conceivably come at us from any direction, so just because a rock comes closer to the Earth than geosynchronous satellites doesn’t mean it crossed the actual orbit that those satellites occupy (in the same way that two planes can occupy the exact same latitude and longitude, but won’t collide because they’re at different altitudes).

  27. Ray

    How big does an object have to be to make asteroid status? 25 meters to me is just a good-sized rock.

  28. Wzrd1

    @Peter B, the biggest risk if ANY asteroid larger than a pea hitting a satellite is a risk to both the satellite (larger than that pea, one pretty much can write off the bird) AND to other satellites in similar orbits. Yes, geosynchronous orbits are “stationary” regarding a fixed location on Earth, but make an averaged elliptical orbit from debris from impact, you get a cloud of hazards.
    This is far, far more apparent for NEO satellites, as there are far more satellites in those orbits than in geosynchronous orbit. That was illustrated a few years back when an Iridium satellite was knocked out by debris from a long “extinct” bird. Or when the Chinese tested their anti-satellite missile, leaving a large cloud of debris that caused the ISS to have to be moved much later.

    @Ray, ANYTHING coming in toward Earth is either an asteroid (even dust grains can be considered as such) or comet. THAT is dependent on orbital characteristics.
    25 meters sounds like a good sized rock, until it comes toward you around mach 25!

    As for risk to Earth from something this size, we’ve monitored 15-20 meter meteors exploding fairly often with our nuclear weapons monitoring systems. They typically detonate many miles above the surface of the Earth. At worst case, it’d likely explode at low altitude (3-6 miles AGL), causing very similar effects to the Tunguska event. Most likely and common, it’ll begin to break up, larger parts stay together until around 20 miles AGL, then it explodes harmlessly.
    Now, if we have an accurate path for entry, we can gather small chunks (ala “Meteor men”) for study, learning more about density and detonation of meteors.
    As this is going to be a clean miss, it’s a moot point.

    Hey, Phil. You’ve been monitoring its trajectory. How much is the Earth perturbing that pebble’s orbit? That close should have a rather moderate effect on its orbit, though I doubt it’ll be “evicted”.

  29. Alex

    Nice article!
    I just wonder…is it within the realm of current technology and rocket propulsion power to deflect the asteriod trajectory enough to capture it within an earth orbit? Obviously it depends on the mass and energies involved, but it would indeed be awesome to capture a second moon in low orbit, perhaps even a (rich) tourist attraction.
    Greetings fron Valdivia, Chile. I used to live in Boulder in the late 90,s. Wonderful little town!

  30. Nigel Depledge

    R3alist1 (22) said:

    So….why do we look for them if we don’t have anything in place to remove the threat again? I must’ve missed that memo…..

    So, without data on how many of these things are out there and how close by us they pass, how would we ever get funding for projects to work out how to deal with one that’s going to hit?


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