(99942) Apophis

See also: Apophis (homonymy)

(99942) Apophis (provisional name 2004 MN4 ) is a Astéroïde geocroisor which was discovered in June 2004. Measuring approximately 250 meters length, made up of iron and weighing 20 million tons, it follows an orbit close to that of the Earth which it twice crosses with each one of its revolutions that it carries out at the speed of 5 km/s.

The first observations of the asteroid tended to give strong a Probabilité (the probability climbed to 1 chance out of 20 on December 27th) of a Collision with the Ground the Friday April 13rd 2029. The asteroid had then been classified on level 4 on the scale of Turin, which was a single case. However, of news Observation S brought more precision on its trajectory and drew aside the possibility of a collision with the Earth or the Moon for 2029. Indeed, the asteroid will pass very close to the Earth then of: 32000 km.

Any risk is not excluded: at the end of June 2006 NASA evaluates the probability of collision between this asteroid and the Earth during the 100 following years with roughly 1/45000, the date of the most probable collision being located in 2036, also in the neighborhoods of on April 13rd. These probabilities surely will decrease with time and the future observations.

The asteroid is classified more only on level 0 on the scale of Turin.

Effects of an impact with (99942) Apophis

Apophis being a Siderite, therefore a very dense and nonporous body, if it follows a trajectory of collision with the Earth, its speed at the time of the impact will be approximately 12 km/s. Knowing its physical parameters, the astronomers estimate that a collision with the Earth would release an energy being able to reach the equivalent of 1.5 WP of TNT.

Statistically, such an event occurs only once every 25000 years and such an impact forms a crater 5 km in diameter.

As comparison, the atomic bomb which exploded above Hiroshima the August 6th 1945 had a power of approximately 15 kilotons, i.e. developing 100.000 times less energy than Apophis.

If it touches the ocean, the impact of Apophis will involve a Tsunami (tidal wave). If it falls off California for example, the simulations presented on the site of Planetary Society indicate that the tsunami will form a 17 m height wave which will break to 100 km/h on the mégapoles, the vague amount to the 4th stage of the dwellings.

If it strikes the ground without disaggregating, in worst case (impact of a siderite on a mégapole) it will cause extensive damage in a ray which can exceed several hundred kilometers and kill several million inhabitants. Following the dust released in the atmosphere, it could result from it one winter which could last several years.

However all these scenarios catastrophes and in particular their amplitude must be refined according to the new data. None of them can be currently confirmed and will not be it before several years even several decades.

Its discovery

(99942) Apophis was discovered the June 19th 2004 by Roy Tucker, David Tholen and Fabrizio Bernardi of the UHAS ( University off Hawaii Asteroid Survey ), from the observatory of Kitt Peak in Arizona and it was observed during two nights. The December 18th 2004, the object was studied again since the Australia by Gordon Garrad of the Siding Spring Survey. Other observations, the following days, throughout the world, made it possible the Minor Planet Center to confirm the relation existing between this asteroid and that discovered in June. The automatic system Sentry of calculation of NASA thus could calculate the foreseeable trajectory of the asteroid and deduce the possibility of an impact from it on Friday, April 13, 2029.

Risk impact

In 2004, the precision of calculations indicated that Apophis would be located in 2029 at more close to the Earth at 4 times the distance the Ground-Moon. Later observations and calculations made it possible to refine the forecast and one considers from now on that any risk is isolated.

On the other hand, if on April 13rd, 2029 it passes in a zone of space baptized " the hole of the serrure" and broad, with its next passage in 2036, it 600 m is likely to strike the Earth.

Currently, the collision risk is programmed for on April 13rd, 2036. According to the experts of program NEO of the JPL, it is of 1 chance out of 12000 and risks it impact of 0 at the most on the scale of Turin, in other words without consequence.

In the worst case, the risk of impact is of 1 at the most on the scale of Turin, and thus with the local consequences described above.

These data will be refined in the years to come because they are always dubious owing to the fact that the orbit of Apophis like that of all the other bodies, is sensitive to the initial conditions which arise from the " laws of the chaos" and affected by the gravitational disturbances generated by the other bodies of the solar system and the heating effects.

External bonds

NASA: evaluation of the risks posed by (99942) Apophis during the 100 next years (updated page regularly)
NASA: list principal threats of collision with an asteroid during the 100 next years (updated page regularly)
(99942) Apophis '' Near-Earth Asteroid '', information regularly updated on the asteroid.
Article of NASA of December 2004 showing the cloud of the possible trajectories
Article NASA on the variation of the possibility of a collision on April 13rd, 2029.
Dossier 20minutes.fr on the possibility of a collision with Apophis in 2036
will Apophis strike the Earth in 2036? based on the data of the JPL and the center Hearts of NASA.

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