An asteroid missed us last night

By Phil Plait | January 13, 2008 10:30 am

I just learned via the Royal Observatory Greenwich blog that asteroid 2008 AF3 passed pretty close to the Earth last night — 475,000 kilometers from us — just outside the orbit of the Moon. It won’t hit us, but it was a close enough shave to be somewhat interesting.

The asteroid was discovered on January 10, just three days ago, and has an elliptical orbit that maxes out at the orbit of Mars and brings it in to the Sun as close as Earth’s own orbit. This pass is close enough to change its orbit, so I’ll be interested in seeing what the orbit looks like after it swings by.

2008 AF3 is pretty faint (it’s small, though I cannot find its actual size), and will only be viewable with biggish ‘scopes — at a max magnitude 14, it’s less than one-thousandth as bright as the faintest star you can see with your naked eye. I expect there will be plenty of amateurs getting images of it, though. If you get any, post them to BAUT! A skymap of the flyby — and for many other asteroids too — is at Tom’s Asteroid Flyby page, a very cool resource that I have now bookmarked.

Interestingly, Tom’s page has it approaching a bit closer (380,000 km) than what’s at the JPL page (475,000 km). I’m not sure which is correct, but both mean it was a clean miss.

We’re getting another near miss at the end of the month, too. This is a good time to be an asteroid hunter!

CATEGORIZED UNDER: Astronomy, Cool stuff, Science

Comments (15)

  1. Michael Amato

    A lot of these near misses are asteroids that were just discovered. I honestly believe if an asteroid should hit us, it would be without any warning. Some of these asteroids are discovered only after they have missed us by a close Margin. The reason they are hard to spot is because they sometimes approach us from the direction of the sun’s glare. A good place to track these asteroids is spaceweather.com.

  2. The ROG blog entry says “The 27 metre diameter”.

  3. Michael Lonergan

    If they discovered one on a direct collision course with us (at least if the area where I live), I don’t think I’d really want to know. Instant vaporization seems much more desirable than worrying about what to wear for three days.

  4. Yeah, Ned (as I know you know, but I’ll say out loud for others :-) ), a size can be estimated from the brightness and distance, but I didn’t see anything on the JPL page about it. I need to look into how the size is calculated; there are lots of other effects as well (albedo assumptions, phase, shape, etc.).

  5. Jeff Wilson

    I agree with Michael, no news would be good news in that case. ;) caught Phil on coast to coast the other night, great show Phil!!!! Haven’t had my telescope out in awhile, after listening to Phiil with George Noorey I guess its time to roll back the roof to the “gak shack” and get some observing in.

  6. tacitus

    If they discovered one on a direct collision course with us (at least if the area where I live), I don’t think I’d really want to know. Instant vaporization seems much more desirable than worrying about what to wear for three days.

    Well, depending on the size of the asteroid and where you live (i.e. a small town vs a big city) then three days could be plenty of time to get out of the way (assuming you do more than decide what you want to wear).

    I would rather know and have a chance over not knowing and having no chance.

  7. The problem with an unannounced asteroid strike – especially one that makes the billion-to-one shot of hitting a major metropolitan area – is the Mutually Assured Destrction that will follow in the subsequent nuclear exchange.

    Well, that’s one of the problems.

  8. DLC

    Harold, your reasoning is flawed.
    an asteroid impact would not be mistaken for a nuclear event.
    a small one would barely be noticed, while a huge city-destroyer would not possibly be mistaken for anything other than what it was.
    An “apocalypse scale” impact would not leave anyone left to give the orders to launch weapons.

  9. On that note, can’t wait for Phil’s new book! :D

  10. Thanks for telling us about the near miss. Guess I’ll go change my underwear now.

  11. Tako Nigiri

    Michael Lonergan said:
    “I don’t think I’d really want to know. Instant vaporization seems much more desirable than worrying about what to wear for three days.”

    I have to agree and it’s possible it could happen that way.
    If I never get to post again, I like to thank the Bad Astronomer for a great website.

  12. StevoR
  13. Quiet_Desperation

    Well it woke *me* up. Man, am I ever a light sleeper.

  14. Bruce

    Hey! We are still alive.

    We should wait now for 2012.

    Hmff…..

  15. tracy

    we saw what looked like heat lightening and sparkles last night in SD followed by a huge boom that was unlike any thunder ive ever heard and that was it some people are saying an asteroid fell between herriod SD and eureka SD ANYONE HAVE ANY INFO?

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