• Question: when is the next asteriod going to hit???(i need to be prepared!!:):):):) )

    Asked by mayerar01 to Carol, Ellie, John, Philip, Rebecca on 3 Jul 2012.
    • Photo: John Welford

      John Welford answered on 3 Jul 2012:


      It sounds like what you need to be aware of is the Torino impact scale:
      http://en.wikipedia.org/wiki/Torino_Scale

      This gives a rating to different objects, based on how big they are (so how much damage they would do to Earth) and how likely they are to hit. The scale goes from 0 to 10, with 0 being no hazard and 10 being a global catastrophe!

      You’ll be glad to know that there has never been an object rated above 4. This was the near earth asteroid “99942 Apophis”, and this was downgraded to zero when we had more accurate predictions about it.

      Currently there are two potential impacts that are rated above zero:

      “VK184” is an asteroid at level 1. It has about a 1 in 1820 chance of impacting the Earth during June 2048 (or 99.945% likely to miss). It is estimated to have a diameter of 130 meters, and travels through space with a speed of 15.63 km/s relative to the Earth.

      “AG5” is also rated at level 1 with a 1 in 500 chance of impact on 5 February 2040 (or 99.8% likely to miss). It is estimated to have a diameter of 140 meters.

      When we have more accurate predictions about their trajectory then they will probably be downgraded to zero as well. I hope that makes you feel safer!?

    • Photo: Rebecca Lacey

      Rebecca Lacey answered on 3 Jul 2012:


      Little objects, such as small asteroids, frequently collide with the Earth. Large asteroids (bigger than 1km in diameter) hit the Earth around every 500,000 years. Bigger collisions with asteroids bigger than 5km in diameter (that’s massive!!) happen about once every million years!

      We don’t often hear about collisions because when the smaller asteroids enter the Earth’s atmosphere they burn up and are vaporised so nothing actually “hits” the Earth. Objects with diameters smaller than 10 m are called “meteoroids” (“meteorites” if they strike the ground). An estimated 500 meteorites reach the surface each year, but only 5 or 6 of these are typically recovered and made known to scientists.

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