Earth Crossing Comets are definitely something to fear, and one only has to remember the Levy Comet that smashed into Jupiter to be reminded that the Earth is not nearly a safe haven for life on the surface of this pale-blue-dot as one might think. Of course, this should be nothing new to humans, as there have been many such incidents in human written recorded history of such catastrophic like events – a couple of which may have changed human religious views in past periods.
And let’s not even get into what may have killed off a once proud species with a 450 million year run at the top of the evolutionary food chain, yes, I speak of the Dinosaurs and the theories that a comet or major asteroid ended their reign. Luckily, scientists and specifically a group of highly skilled astronomers such as David Morrison and others have worked quite hard in the census tracking of NEOs or Near Earth Objects, and NEAs or Near Earth Asteroids as well as comets. This is a good start, still, they admit that they most likely have not found them all yet.
And an acquaintance of mine reminds me of the billiard effect, where asteroids in the main asteroid belt collide with each other, and such collisions or being knocked out of the belt by a fast mover (comet) احسن جامعه فى مصرcould send one heading straight for us. And it has been estimated that some comets lose their inertia and evolve back into asteroids and retire to the grassy pastures of main asteroid belt. So, NEOs and comets are constantly changing – adding and subtracting.
Each time an NEO hits a planet, well, you can take that out of your census too. The Earth Orbit Crossing objects are the most scary, especially the periodic ones which will “all” eventually hit us over the next many millions of years, or they might hit something else saving us or sparing Earth from the hassle. Still, the predication of these objects is not so easy, as most of them spin, they have different shapes, different orbits, different masses, and they also encounter other non-gravitational planetary and solar forces.
This is why scientists can only give us a percentage of risk in a given period and why they keep adjusting it as they go based on the latest movements. “What we need is a better tracking system, one which is a 24/7/365 forever tracking system,” notes my acquaintance, and I must say, at least on that point we concur. What say you? Please consider all this and email me if you have information which might help our think tank.