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OAS > Asteroid (99942) Apophis

Sormano Astronomical Observatory

Asteroid (99942) Apophis, at the moment the only one asteroid
with a well know orbit that will close approach the Earth on April 29, 2029.

(99942) Apophis, the Greek name of Apep - the Egyptian god of evil and destruction, was discovered by Tholen D.J. and Bernardi F. on June 19, 2004 from Kitt Peak (code 695) but observed over two nights and rediscovered on December 18, 2004 by Siding Spring Survey (code E12).

Here are available AVI(about 4 Mb) or GIF (about 1 Mb) animation of n.6 CCD images taken at Sormano (Italy) on December 30, 2004 when the object was just 14° above the horizon , crossing Cetus.

In reference to the nominal orbit solution, calculated using Arecibo radar astrometry, (99942) Apophis will pass very close from the Earth (geocentric distance) at about 36000 Km on April 13, 2029 (for more details see our TECA and MBPL lists ).

This object has an estimated diameter of about 330 meter and after the close encounter quoted above that will change its orbit, a close approach is expected in 2036 when a very small risk of collision with our planet has not yet totally removed. Currently there are investigation to plan a spacecraft rendezvous with this asteroid both to perform more accurate study on its chemical composition and to deflect it using a "gravitational tractor", if its orbital path, in the next future, it would be found in a collision's route with us. A good opportunity to apply this method could be in 2013.

Using updated information, NASA scientists have recalculated the path of a large asteroid. The refined path indicates a significantly reduced likelihood of a hazardous encounter with Earth in 2036 but more measurement are needed.

(99942) Apophis will be so close to the Sun until 2011 and too distant for useful radar measurement until 2013.

See the BBC Online article (March 25, 2010) "Cuts cast doubt on asteroid plan"

For more information please see JPL reference:

  • Predicting Apophis' Earth Encounters in 2029 and 2036
  • Publication "Predicting the Earth encounters of (99942) Apophis"
    by Jon D. Giorgini, Lance A.M. Benner, Steven J. Ostro, Michael C. Nolan b, Michael W. Busch
  • NASA refines asteroid Apophis'path toward Earth
  • JPL' animation "apophis unknown_bias"

    or
    NEODYS summary page:

  • NEODYS - (99942) Apophis

    See also:

  • (99942) Apophis from wikipedia
  • JPL orbit diagram
  • B612 Foundation
  • B612 Foundation - gravitational tractor
  • NASA Ames Research center
  • Planetary Society competition prize
  • JPL Sentry System
  • NeoDys Risk page

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    Web Curators: F. Manca, M. Carpino
    Last modified: November 03, 2011