How secure is our space?

According to the latest theory, during the time, when all planets were been formed in our solar system, some of the matter, which orbited the sun, could not come together and form a planet. This happened, because this matter had not the necessary mass to fall together. Moreover, due to Jupiter’s strong grafitation field, most part of this loose matter was spread apart. In other words, a planet formation was practically impossible and asteroids were formed instead. These rock similar objects formed the current asteroid belt.

Most asteroids are made of rock, but some are composed of metal, mostly nickel and iron. They range in size from small boulders to objects that are hundreds of miles in diameter. A small portion of the asteroid population may be burned-out comets whose ices have evaporated away and been blown off into space.

In the asteroid belt there are millions of asteroids from different sizes circling the sun in a more or less regular orbit. Their path is situated between Mars and Jupter. The first asteroid discovered is the largest one; it has 933 Km in diameter (almost as big as Texas). It was discoverd by Giuseppe Piazzi in January of 1801; its name is Ceres. There are also divers others big asteriods (100-600 Km) and an enormous amount of smaller ones (1 Km). Every month hundreds of new asteroids are discovered.

Comets are bodies of ice, rock and organic compounds that can be several miles in diameter. Comets are thought to originate from a region beyond the orbits of the outermost planets. Scientists believe that gravitational perturbations periodically jar comets out of this population, setting these “dirty snowballs” on orbital courses that bring them closer to the Sun. Some, called long-period comets, are in elliptical orbits of the Sun that take them far out beyond the planets and back. Others, called short-period comets, travel in shorter orbits nearer the Sun.

When comets venture into the more intense sunlight of the inner Solar System, the ices in the comet nucleus begin to vaporize and fall away. The evolved gas forms a tenuous atmosphere around the nucleus called a coma, while the dust previously in the nucleus forms a tail that can be thousands of miles long and sometimes can be seen from Earth. While striking the early Earth billions of years ago, comets are thought to have created major changes to Earth’s early oceans, atmosphere and climate, and may have delivered the first carbon-based molecules to our planet, triggering the process of the origins of life.

If asteroids and comets might have hit our planet Earth some millions of years ago, could they hit us again? How secure is our space?! The probability of a NEO (Near Earth Object) impact increases with the number of objects in our surroundings. We know there are millions of asteroids circling “peacefully” in the asteroid belt. We know there are several comets orbiting the sun in different paths, but there are still thousands of other objects we have not discovered. A project called Spacewatch was founded by Prof. Tom Gehrels and Dr. Robert S. McMillan in 1980. It is a group at the University of Arizona’s Lunar and Planetary Laboratory. This project should catalogue all small objects in our solar system. Till now, there have been thousands of asteroids and hundreds of comets discovered, but there might be thousands of other unknow, maybe threatening objects around us. The most dangerous objects found (NEOs) are constantly observed by NASA and military organizations.

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