Tiny rock to buzz Earth Tuesday

By Phil Plait | October 11, 2010 9:57 am

Artist drawing of an asteroid entering Earth's atmosphereUniverse Today is reporting that an SUV-sized asteroid will pass by the Earth tomorrow at a distance of about 45,500 km (28,000 miles). That’s close, but quite safe! The Earth is about 13,000 km (8000 miles) in diameter, for comparison. The rock will pass around the same height above the Earth’s surface as orbiting weather and communication satellites.

The danger from this asteroid is, for all intents and purposes, essentially zero. The orbit has been nailed down enough to know it won’t hit us (and even if it did, it would almost certainly not reach the ground; rocks that size make it down very rarely, instead exploding high in the atmosphere), and the odds of it hitting a satellite are roughly similar to two dust motes randomly colliding inside a football stadium.


The asteroid, named 2010 TD54, was discovered on Saturday, and will make its closest approach at 11:25 UT (07:25 Eastern US time). It would be a very tough observation for amateur astronomers, though not out of the question. It’ll briefly reach about magnitude 14, within easy reach of a small telescope with a good camera, but it’ll be screaming across the sky at high speed, making it a very rapidly moving target. If anyone can get images or video of it, please let me know!

This rock is interesting. The orbit takes it from 100 million km (60 million miles) from the Sun out to about 430 million km (250 million miles). That means it crosses the orbits of Venus, Earth, and Mars*! Not only that, the orbit is not tilted by very much compared to Earth’s (about 5°), meaning it passes those three planets fairly often — it orbits the Sun roughly every 2.5 years. I suspect this object hasn’t been in this orbit very long. If it had been, it would’ve long ago smacked into a planet. If I had to guess, I’d say in the past it was on a different orbit and got nudged into this one by a gravitational interaction with a planet fairly recently. You can look at the orbit as well on the JPL Near Earth Object browser.

Given its odd orbit and the fact that it’ll make such a close pass, I hope some big telescopes get good data on this flyby. I’m very curious about the origins of this little rock!

[Update (Oct 11, 13:30 Mountain time): A little more info can be found at >the JPL Asteroid Watch site.]

* To be fair, it doesn’t get all that close to Mars, but it does get close to Venus, and obviously the Earth!

Related posts:

30 years, a half million asteroids
Armageddon delayed by at least a century… this time
A good look at a near-Earth visitor
2007 TU24 miss distance update

CATEGORIZED UNDER: Astronomy, Cool stuff

Comments (35)

  1. Ira

    Why are we not trying to capture and harvest data (or rare ores) from it?

  2. Oli

    What do you mean by “it doesn’t get all that close to Mars”? Wouldn’t it have close encounters with Mars at least sometimes? Or is their an orbital resonance between the two? (would be strange considering Jupiter and the Earth are much heavier than Mars)

  3. Grand Lunar

    The fact that we’ve detected an SUV sized object is encouraging to me.
    At least we can spot the small stuff.
    The big stuff ought to be little trouble. I hope….

  4. Ateapotist

    Looking at the orbit shown for this object, I wonder if it stands a chance of being captured by a planet. It would be interesting to have a “new” moon in the inner solar system.

  5. SUV SIZED!?!?!?!?! AHHHHHH! Panic!

    Now if it had been Prius sized, that would be a different sotry.


    Sorry, wired on too much coffee I think.

  6. ASFalcon13

    “the odds of it hitting a satellite are roughly similar to two dust motes randomly colliding inside a football stadium.”

    I clearly remember the last time I heard an analogy like this. It was during a weeklong orientation course at work, and part of the course involved orbital dynamics. The instructor compared the likelihood of two satellites colliding to a pair of Volkswagen Beetles driving randomly around the state of Texas and hitting each other.

    Coincidentally, he was giving that lecture at roughly the same time that this happened: http://en.wikipedia.org/wiki/2009_satellite_collision

    No point really, just an interesting story.

  7. AJKamper

    Phil or anyone else:

    Have we figured out to what extent the asteroid’s orbit will be affected by this pass? It seems to me that two Earth radii would still be close enough to significantly perturb the orbit of such a small object, but what do I know?

  8. RatPunk

    As Grand Lunar says, the fact that we could detect it is encouraging. The fact that we didn’t detect it until two days before it passed is the troubling part.

  9. @Ateapotist (#4) The object’s relative v = 17.53km/s is much much greater than the escape velocity at ~45,000km (geosynchronous satellite move at about 3km/s and the escape velocity at that altitude is about 4.33km/s). Besides, my guess is that any captured object wouldn’t stay captured for long probably a few dozens of revolutions at most.

    @Grand well, the question is really how much we miss. The surveys capable of detecting objects of this size at the distance where it was first seen, observe a tiny fraction of the sky just a few degrees around the ecliptic

  10. Ben

    The best thing we can do from here is to hire a team of oil drillers to embed a nuclear device on the asteroid in hopes of splitting it in two.

  11. ChH

    So … the odds of this asteroid hitting a satellite are approximately eight orders of magnitude less than something like this happening:

  12. Is there any chance that this is a man-made object?

  13. TechBear

    Discovered two days ago? I’m curious: was it its small size that kept it hidden, or is it coming from a region not normally under surveillance?

  14. ChH (#11): actually, that’s a good point. How many pitches are thrown in a game? Around 50 minimum, and more likely 100. There are 162 games per season, and 30 teams. I suspect there are roughly 100,000 pitches every season, and the game’s been played for a century… and a bird got hit once.

    So yeah, pretty unlikely.

  15. 24601

    Could this event be used to help get additional funding for NEO sky surveys? It sounds like a good wake-up-call to government folks and layperson folks alike.

  16. ChH

    I didn’t get specific in the interest of brevity … but I was thinking on a per-pitch basis rather than all of baseball history, and the 8 orders were just based on a ball and a bird being so much bigger than the dust motes in your analogy.

    I did find two other videos of birds getting hit by pitches.

    This bird was spectacularly unfortunate by the way – it got hit by the hardest-throwing starting pitcher since ball speeds became accurately measurable.

    Anyway … like you said twice … our satellites are safe.

  17. “… a gravitational interaction with a planet fairly recently”

    Out of interest, how recent is “recently”? Years? Decades? Centuries? How long would an object in this kind of orbit typically last?

  18. johno

    Everyone knows that 1 in a million chances happen 9 times out of 10

  19. Gamercow

    This is a great example of a story with heavy underlying tones. The takeaway from this article is not that the object was discovered, or that it will be buzzing us, or that it’s too small to do any damage, but that it was only discovered on SATURDAY. If that thing was bigger, and on a direct course, we’d be screwed, you can’t do anything in 2 days.

  20. Oli

    @19. Gamercow: True, but then it would have been discovered earlier.

  21. all4tookie

    As an avid baseball statistician, I can tell you your estimates for number of pitches per game is quite low. The average team throws about 146 per game these days. That equates to about 700,000 per (modern) season.


    However, I don’t think we can be sure a bird was never before hit by a pitch in a game, particularly in the pre-youtube era…

  22. @Oli #20. Not necessarily. Sky Surveys capable of detecting objects as bright as this was when first seen, i.e. beyond 20th mag. (Catalina & Mt. Lemmon, Spacewatch), cover only a tiny fraction of the night sky, just a few degrees around the ecliptic in a single lunation (LINEAR covers quite a lot but doesn’t see beyond V20). There are plenty objects passing us by we don’t see. Also, there’s a possibility that an object’s coming from the direction of the sun (i.e. with elongation <60 degrees) in which case, no ground based sky survey can see it.

    There are plenty of objects tens of meters across discovered within just a few days of passing the perigee, and some only after.

  23. Navneeth

    Gamecrow, for me a couple of days are enough to prepare for the show. You must be slow. ūüėõ

  24. Doesn’t look like a chance for imaging for me tonight. Weather will not cooperate

  25. loonatic112358

    at least it’s not a Hot Fudge Sundae falling Tuesdae

    /supports recycling of bad jokes

  26. #1 Ida

    Why are we not trying to capture and harvest data (or rare ores) from it?

    Science can do some amazingly cool stuff, but the ability to catch an SUV-sized boulder whizzing by at however many thousands of miles per hour is currently not something we possess.

    However, with enough advance warning of the asteroid’s arrival, maybe it is. Not that this is practical, but I’m thinking in terms of “possible” here: It might just be possible to use a probe to “nudge” a very small asteroid headed for a near-earth encounter so that instead of whizzing by, it instead gets captured by Earth’s gravity and goes into orbit. It would be crazy expensive and crazy tough to do. and crazy dangerous if the asteroid is of sufficient size to do serious damage if we screwed up just slightly…. but it might just be possible. Maybe not though, what do I know? Fun to think about in any case. The math involved would be staggering!

  27. It would take rather a large nudge to bring it into earth orbit, enough to vapourise it. Easier would be to alter its orbit with a nudge and use lithobraking for the capture phase. However, this is not much better and probably not a good idea. To get a genuine capture into orbit you need a third body, say the moon. Use one nudge to make it pass close to the moon the right way, the moon takes a big chunk of its momentum leaving it in an elliptical orbit around earth, then another nudge to move its apogee away from the moon to limit the chances of later luna lithobraking.

    All we need now is a nudger.

  28. Robert

    @Oly: Re ‚ÄĒ What do you mean by ‚Äúit doesn‚Äôt get all that close to Mars‚ÄĚ? Wouldn‚Äôt it have close encounters with Mars at least sometimes?

    It’s to do with that 5 degree tilt. By the time it gets out to Mars’ orbit, it is far above (or below) the ecliptic. So it will never get close to the orbit.

  29. Gerry

    Just because it’s orbit is ‘nothing to worry about’ THIS time, the thought of a rock big enough to flatten a small city zipping by just over our com sats is NOT something we should be dismissing. Time to stop gaping at the nuclear-war-starters (if someone gets nervous when a city vaporizes) and start DOING something about them….

  30. reidh

    I can say this, I will never, ever, ever, (again) worry about an asteroid accidentally colliding with another, and or falling out of sky onto the earth near me, without it having been thoroughly data based and catalogued by our eyes in,on,and of the sky.

  31. Albert J. Hoch

    Like AJKamper I too would like to know how the object’s orbit will be changed by this close pass.

  32. Alex

    – Cdn and American astronauts want world to start getting ready for asteroids… VIDEO: Our terrifyingly crowded solar system…CBS News: Jupiter Hit by Large Object, NASA Says…Californian Congressman for Planet X Forsight – The Sky is Falling…Stephen Hawking: “Asteroid Impacts Biggest Threat to Intelligent Life in the Galaxy…Giant propeller structures seen in Saturn’s rings…NASA: Sun’s Nemesis Pelted Earth with Comets, Study Suggests:

  33. jonathan

    Tunguska event

    The asteroid that stuck never touched the ground the effect of the shock wave caused caused the explosion.

    So even if the asteroid doesn’t struck the ground it still may cause damage.


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