Another tiny rock will pass Earth tomorrow

By Phil Plait | May 28, 2012 12:15 pm

[tl;dr: A small 5-10 meter asteroid will pass us tomorrow; it poses no danger to us.]

[UPDATE (May 29, 16:30 UTC): The JPL website for this asteroid has been updated – the rock passed us at the predicted distance of about 14,500 km from the Earth’s surface. The new numbers use 50 observations of the asteroid (the earlier orbit calculations used far fewer), so this looks pretty solid to me. As we knew all along, it was a close pass, but nothing to worry about.]

I recently wrote about near-Earth asteroid 2012 KP24, a house-sized (25 meter) rock. As I write this it passed us safely just a few hours ago, as predicted.

But thanks to scibuff and AsteroidWatch on Twitter, I just learned of another tiny visitor that will buzz past us tonight/tomorrow, May 29, at around 07:00 UTC (03:00 Eastern US time). Called 2012 KT42, this one is even smaller than KP24: it’s probably less than 10 meters across — about the size of a school bus or more likely a minivan. And it’ll be a close shave: though the orbit is still not nailed down, the nominal miss distance is about 14,500 kilometers (8900 miles). That’s a bit bigger than the diameter of the Earth itself.

[UPDATE (19:15 UTC): There’s more info on KT42 in on the Italian Remanzacco Observatory blog (h/t TredySas). There’s also a cool animation made from five exposures of it:

I’ll add more here if I hear anything.]

[UPDATE (19:55 UTC): No new info as such, but Alex Gibbs from the Catalina Sky Survey sent me this nice 4-tile mosaic of the discovery images of KT42, taken with the Mt. Lemmon 60" telescope:

Very cool!]

Bear in mind, it was only discovered last night, so the current orbit is preliminary. Many small rocks that pass close to Earth are discovered shortly before they breeze past us (and some not until after), so this is nothing out-of-the ordinary.

And since some people tend to get upset about these things, I’ll point out that as of right now, it looks like it will miss us. And even if newer observations show it hitting us, this rock is way too small to do any damage. At that size, it’ll break up in the atmosphere and make a spectacular light show, but not much else. This has happened countless times with asteroids this size, like the Peekskill meteor in 1992, or the more recent fireball over California last April. These can produce meteorites which fall to Earth, but the odds of getting by one are so small they’re basically zero.

Put it this way: the Earth has a surface area of more than 500 trillion square meters. Your surface area is less than 1 square meter (as seen from above). Those are pretty good odds you’ll be OK.

Another way to think about this is that rocks this size pass us all the time, but you never hear about them hurting us; that’s because they don’t! The smaller the asteroid the more common they are, but the less they can do to us. At this size, there’s no danger.

And as usual, I’ll point out that this discovery is a good thing! It shows we can find them, and that’s important. If we ever do discover an asteroid on a collision course that’s big enough to hurt us, the first step is to find it. And we’re getting better at that all the time.

Related Posts:

Small asteroid to buss Earth on May 28
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


Comments (23)

  1. cos

    So probably no chance to see it over central Europe tomorrow morning, will be like 9 AM, too much sun …. but have to ask: is it know where could be visible?

  2. BeerMe

    Phil, do these asteroids pose risks to our space hardware?

  3. Quick! We need to launch a space shuttle to its surface and nuke it or we’re all doomed!

  4. cos

    No need for launch, we have the dragon protecting us high in the skies ūüėČ

  5. chief

    AAaiiee… WE”RE GOING TO DIE.

    (well, in 4 to 5 billion years anyway)

    This helps show that our detection methods are paying off in the sizes and advanced notification of said bodies before they are in our neighbourhood.

  6. Ben

    14500 kilometers, eh? Who cares? Maybe if it was going to clear the ground by 30 or 40 feet there would be cause for alarm.

  7. Chris

    With all these asteroids missing the Earth, I can’t help but feel unloved. We’re a perfectly nice planet, why don’t they want to hit us?

  8. Dragonchild

    @8 Chris –
    I’ll hit you if it’ll make you feel loved. ūüėÄ

  9. Blargh

    BeerMe: while it does pass within the orbits of our satellites (geosynchronous orbit is around 40000 km) the risk of an asteroid that size hitting a satellite is comparable to that of it scoring a direct hit on a person. It’s so tiny that it can be safely ignored.

    For satellites, the collision risks are micrometeoroids (because there are so many of them) and “space junk” – man-made debris, made dangerous because its orbit overlaps that of things we actually care about.

  10. VinceRN

    How cool is it that we can spot a rock the size of a truck tens or even hundreds of thousands of kilometers away?

  11. Cairnos

    @Mike D – Hey at least a nuke could conceivably do something to this one, although the tension of drilling to 5 metres might be a tad underwelming:

    “Prepare to drill…..drill!..Stop!!, damn we overshot again, move over a few metres and we’ll try again.”

    “Uuh sir, we’re running out of asteroid already

  12. Mark

    I think we are missing a chance to observe many things about space if we do nothing. Here is an opportunity to use the asteroid as a platform to place survey equipment. To observe the places the rock passes through, to develop a more complete image of the effect of gravity on close approaching space objects, methodology and equipment for landing a craft on a small unfriendly moving target, and I’m sure many other things. Including of course, the best way to approach the danger it or any other object may create to our planet. One must wonder what eliminating a large body in space, or even deflecting it, would do to other bodies it has passed near in its now changed orbit. Of course, it wouldn’t be a bad idea to place a good sized nuke inside the damn thing in case it hits the window either. Beam me up, Scotty.

  13. Messier Tidy Upper

    This story reminds me of the recent (non)scares of falling satellites.

    Like them, if these very small asteroids did hit Earth – which they won’t – odds are pretty high that it would land in one of the oceans or in a desert area.

    Mind you, in some ways for a small asteroid making a big splash and a consequent tsunami is actually more of a problem than a land landing would be! Pretty sure their mass, speed and thus kinetic energy being transformed into heat, light and shockwave is considerably greater than any artificial satellite we’ve yet built – even the ISS.* Right?


    * Which, btw., like Mir, Skylab and the Salyuts is hollow and would break up on re-entry.

  14. @2. BeerMe : “Phil, do these asteroids pose risks to our space hardware?”

    A very, very, *very* exceedingly remote one for satellites and space stations that cannot move out of the way quickly enough just possibly.

    To add to what (#10.) Blargh said, most working satellites and the International Space Station are capable of shifting their positions using thrusters and thus can avoid anything large enough to cause serious damage.

    The ISS has in fact been forced to take evasive action to dodge space junk on occassion. When a particularly worrisome piece passes close by the crew can be forced to take shelter in the Soyuz capsule which could return them to Earth if the Station was too badly hit. (See for example the article linked to my name here.)

    A dead satellite that’s out of fuel or otherwise unable to be controlled may be hit one day – and in a chain reaction could well multiply the amount of space junk up there but given the relative size of the satellites versus the sheer amount of space in, well, space, its highly unlikely to happen for a very long period of time.

  15. puppygod

    With all these asteroids missing the Earth, I can’t help but feel unloved. We’re a perfectly nice planet, why don’t they want to hit us?

    It is because we have too shallow gravity well, isn’t it? Aw, shucks. Now I have a small gravity well complex.

  16. Marc


    We are all going to die much earlier. More like within 130 years considering that the oldest person is not much more than 120 years. :-)

  17. Pete Jackson

    Just picked up on my subspace radio – the tiny inhabitants of a small space rock have recently been most alarmed at seeing the third planet from the Sun, always just a pin-point of light, suddenly grow in size and is now looming over them as an enormous menace. Fortunately, these inhabitants, living in such a harsh environment, have developed enormous technological capabilities to cope, and have already devised a solution to their peril. Their plan is simply: NUKE THE EARTH!

  18. this rock is way too small to do any damage” , Yeah – “too small.” An iron ball 10 meters in diameter masses 4100 tonnes. Give it a meager 5 miles/second. KE = (mv^2)/2, plus mgh. 4.186×10^12 J/kt

    [(4.1×10^6 kg)(8.047×10^3 m/sec)^2][(2)(4.186×10^12) = 31 kilotonnes

  19. Kevin in Sacramento

    An impact by 2012 KT42 would produce an upper atmosphere air burst equivalent to 11 kt TNT, roughly equal to Hiroshima’s Little Boy. The asteroid would be vaporized as these small impacts occur approximately once per year. A comparably-sized object caused the Sutter’s Mill meteorite in California on 2012 April 22.

  20. smittypap

    Thanks for keeping us updated, Phil. Passing a large stone is never easy.

  21. Matt B.

    @0 Phil: I think you’re missing the word “hit” in the fourth to last paragraph–“but the odds of getting hit by one are so small they‚Äôre basically zero.”

  22. Vetr

    I think, if it had been up to me, I might have called it something that didn’t include ‘KT’.


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