Uncomfortably close: 5.4km diameter asteroid '4179 Toutatis' to fly by Earth at just 0.046au on 12 December
Wed, 22 Jun 2011 11:49 UTC
= about 18.0 times distance to the moon (=ld)
This Asteroid will makes its next closest approach at 12-29-2016
It has a cycle of about 4 years and 18 days
A potentially hazardous object (PHO) is an asteroid (PHA) or comet (PHC) with an orbit such that it has the potential to make close approaches to the Earth and a size large enough to cause significant regional damage in the event of impact. These objects are monitored by NASA with contributions from others including amateurs. The reason they can become hazardous is that their trajectory can variate due to gravitional fields from Planets or Stars (ore other objects). Overall the chance of a potentially hazardous event due to these objects is about once in 10,000 years.
Overall the chance of a potentially hazardous event due to these objects is about once in 10,000 years.Actually, no. Professor of planetary science, John S. Lewis, found that it's more like once every 300 years:
Comet and Asteroid Impact Hazards on a Populated Earth: Computer Modeling by John S. Lewis