Odds of Apophis Apocalypse – We’re OK

A close call but it won’t be a catastrophe. Don’t worry. Yet.

Apophis – a ‘potentially hazardous’ asteroid – flies by Earth on Wednesday | guardian.co.uk.

Asteroid Apophis arrives this week for a close pass of Earth. This isn’t the end of the world but a new beginning for research into potentially hazardous asteroids.

Apophis hit the headlines in December 2004. Six months after its discovery, astronomers had accrued enough images to calculate a reasonable orbit for the 300-metre chunk of space rock. What they saw was shocking.

There was a roughly 1 in 300 chance of the asteroid hitting Earth during April 2029. Nasa issued a press release spurring astronomers around the world to take more observations in order to refine the orbit. Far from dropping, however, the chances of an impact on (you’ve guessed it) Friday 13 April 2029 actually rose.

By Christmas Day 2004, the chance of the 2029 impact was 1 in 45 and things were looking serious. Then, on 27 December astronomers had a stroke of luck.

Looking back through previous images, they found one from March on which the asteroid had been captured but had gone unnoticed. This significantly improved the orbital calculation and the chances of the 2029 impact dropped to essentially zero. However, the small chance of an impact in 2036 opened up and remains open today.

We must accept that someday, we will be faced with the problem of dealing with an asteroid that will hit. Perhaps we won’t notice a small one until it’s too late and, if it hits a populated area, it could be destructive.

Wednesday’s pass of Apophis is only close by astronomical standards – 14.5 million kilometres above Earth’s surface. So we shouldn’t be concerned. Astronomers will get a nice view of the flyby. But on April 13 of 2029, Apophis comes in for a mighty close shave, less that one-tenth the distance of the moon and closer even than communication satellites that orbit Earth. That’s a bit nerve-jangling.

For more on the odds of our demise, see <a href=”http://www.amazon.com/gp/product/0143116045/”>Death from the Skies!: The Science Behind the End of the World, Philip Plait Ph.D.</a>. It makes you feel scared and relieved AT THE SAME TIME!

Not happening. Yet.

  5 comments for “Odds of Apophis Apocalypse – We’re OK

  1. Massachusetts
    January 7, 2013 at 9:06 AM

    Fortunately these impacts are unlikely, but even a hit in the middle of an ocean could trigger a Tsunami which would be bad for the coasts (and a few fish perhaps).

    But the religious mania this would trigger would be a problem I suspect: the impact seen as God’s judgment, Etc. We see that with hurricanes so an asteroid strike would really bring this kind of thinking out of the woodwork.

    However, I’ve read that, if given lots of lead time, we could use the gravitational pull of a probe, even a relatively small one, to deflect an object just enough for a miss (accurate calculations assumed of course). Has anyone read more about the feasibility of that approach

  2. D.Walker
    January 7, 2013 at 9:07 AM

    It’s a shame we can’t place a tracking device gently on these near passing asteroids. Some unforeseen gravitational influence could possibly alter trajectory enough to put us in harms way. An impact in the ocean would mean horrible tsunamis, one on land could trigger a super-volcano eruption, an air-burst explosion could start massive forest fires.

  3. Chew
    January 7, 2013 at 12:37 PM

    They call it the Gravity tractor. The amount an asteroid needs to be deflected depends on how much time we have until it hits. An asteroid that will hit in a year “only” needs to have its velocity adjusted by 0.2 m/s. Add more time and the required velocity drops.

    Here’s an Earth Impact Effects Program to model all the destruction caused by an impacting asteroid. For Apophis’ 2029 close approach use these values:
    Projectile diameter 270 meters
    Projectile density 2600 kg/m³
    Impact velocity 12.58 km/s
    Use a 90° impact angle for maximum destruction! The more acute the angle of impact the more the atmosphere will slow it down.
    You can have it hit water and make a tsunami. Keep in mind tsunamis can grow up to 10 times or greater that predicted height as they run ashore.

  4. Arthur M.
    January 10, 2013 at 2:26 PM

    The B612 Foundation is attempting to not only track down possible interception asteroids but to look into the possibility of exploited them along with other deep space mission. Learn more about them here:


  5. Arthur M.
    January 10, 2013 at 2:39 PM


    New orbital analysis of Apophis rules out collision with the Earth in 2036.

    We knew that the 2029 approach will be close but we could not project it well enough to rule out a possible collision in 2036, but the observations taken from Apophis’ current pass have refined our understanding of its orbit so that we now know there will be no collision in 2036. Further data still being gathered should allow us to project its path even further into the future.

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