Comets are delicate and transient visitors from our Solar System’s frigid, dark twilight regions beyond the orbit of the outermost major planet, Neptune. These dazzling objects come screaming into the warm and well-lit inner Solar System, close to the brilliant fires and melting heat of our Sun, with their sparkling thrashing tails flashing as they streak across the sky. Alas, when alien stars pass too close to our Solar System, they can push these frozen objects out of their original home in the remote Oort cloud into the inner regions around our Star, and thus stellar close encounters are an important factor in determining the risk of dangerously large cosmic impactors striking our Earth–with catastrophic results. In August 2017, Dr. Coryn Bailer-Jones from the Max Planck Institute for Astronomy in Germany announced that he has used information derived from the European Space Agency’s (ESA’s) Gaia satellite to give the first systematic estimate of the rate of such close stellar encounters of the worst kind. According to the new research, every million years, up to two dozen alien stars float within a few light-years of our Sun, making for an almost-constant state of tragic perturbation–and just such a dangerous star will invade our Solar System in 1.3 million years, potentially sending comets screeching towards Earth.
The Oort cloud, named in honor of the Dutch astronomer Jan Oort (1900-1992), is a still-hypothetical cloud composed primarily of icy comet nuclei that is believed to surround our Sun at a distance of about 50,000 to 200,000 astronomical units (AU). One AU is the average Earth-Sun separation, which is 93,000,000 miles. This very distant cloud, composed of frozen comets, is thought to form an enormous shell around our entire Solar System.
Comets crashing down on our planet are among the most destructive of cosmic catastrophes. Probably the best-known disaster of this sort was the mass extinction event, that occurred approximately 66 million years ago, that hastened the demise of the dinosaurs. This mass extinction paved the way for mammals to emerge, evolve, and survive on Earth. However, it has not been definitely determined if the impactor, in this case, was a comet or an asteroid.
Catastrophic impact events that cause regional or global destruction on Earth are rare, and occur at the rate of only one every million years. In addition, monitoring systems provide a reasonably complete inventory of larger comets and asteroids–and not one is on a collision course with Earth.
Nevertheless, the threat of such a catastrophe is serious enough to require investigation. The outer limits of our Solar System, where the Oort cloud is located, is believed to host a multitude of frozen, icy comet nuclei. The gravitational nudges of wandering stars can push these comets inward towards our Sun–and some of the icy objects will migrate into the inner Solar System where Earth is located. For this reason, these objects can potentially enter a collision course with our planet. This is the reason why a scientific understanding of these stellar encounters and their properties is necessary. 480p mkv movies download