Introduction Asteroids are rock like bodies orbiting the Sun like the other planets are orbiting. As compared to planets, asteroids are much much smaller in size and are present in our solar system at places though the majority of them are present in a belt between Mars and Jupiter which is known as asteroid belt. There are lot many number of asteroids in fact millions of them in our solar system.
There are some asteroids which even cross the orbital paths of the planets. These asteroids have a probability of colliding with the planets though it is a very rare event. Some asteroids are orbiting in very eccentric elliptical orbits.As per scientific study and research it is known that the solar system came into existence by condensation of a huge gaseous mass from which sun and different planets were born. It is believed that in the asteroid belt the small fragments out of condensation could not form a planet and remained in a scattered way and since then rotating around the sun. These asteroids are in irregular shapes and different sizes.
The small asteroids fall on the earth either as dust or small bodies of rocks and mostly go unnoticed until unless they fall in populated area. On scientific analysis they are found containing clay, metals etc which are common constituents of rocks. Technically these smaller asteroids falling on earth regularly are termed as meteorites.
Expert astrophysicists of Astrophysics Research Center at Queen's University Belfast (QUB), North Ireland, UK have warned that there is a possibility of asteroid hit in future in the year 2027 when a large asteroid is going to pass very near of the Earth. If so the destruction caused by this catastrophic event will be of on a very large scale.
History of Asteroid hits on Earth Time to time in past asteroids have hit Earth and though the smaller ones were burned out while entering the Earth atmosphere and did not do any harm but the larger ones are a matter of concern as they will not be fully burned and mixed with Earth atmosphere but hit it and will cause immense destruction. Generally at the hitting time a large part of the asteroid goes deep inside the Earth and in this process a large crater is also created. In geological studies, while studying for origin of earth and its evolution, the imprints of such craters are seen at many places in the subsurface of the earth.
Though big asteroids have also hit Earth but the one which was physically observed and felt was in the year 1908. This hit happened in a place in Russia towards the direction of Siberia and is known as 'Tunguska event of 1908'. The big asteroid exploded in the atmosphere before falling and its hot pieces scattered all over the place which was a forest area at that time. It is estimated that an area of about 1990 square kilometers was flattened and burned out due to the impact of those fragments. As it was a forest area no causalities were reported.
The energy released in this hit was immense and has been estimated approximately as 400 times as much power as the atomic bomb dropped on Hiroshima. From this one can imagine the destruction caused by these asteroids specially when they are bigger.
Present Asteroid As per the study of Astrophysics Research Center at Queen's University Belfast (QUB), North Ireland, UK it is expected that a large asteroid may pass very near to Earth and may hit Earth in the year 2027 causingimmense destruction. There are many astronomical agencies which are monitoring the near earth objects for threats and presently thousands of such bodies are closely monitored and the asteroid which is expected to hit Earth in 2027 is one of them.
European Research Council's NEOshield-2 project is also one project which is engaged in identifying any potentially dangerous asteroid, which could strike Earth in the future, and to find scientifically some effective methods or techniques to prevent such a collision like deviating it on its way or burning it muchabove in the atmosphere. It all appears like science fiction today but with increasing advancements in space sciences and technologies could be achievable in near future.
Conclusion The scientific expectations of research center may come or may not come true but the fear of asteroids hitting Earth will always be looming overhead. We are so far lucky that there is no big asteroid hit in recent times.
The author has given in simple words the whole physics and chemistry involved in asteroids. I have also read about the Russian incident which was narrated by the author.
When I was doing my M.Sc. in Andhra University, vizag in the year 1977, there was a very big issue about falling of a Skylab from the sky on the earth and it was told that it will destroy a lot of mankind on the earth. But luckily nothing happened and all were safe. In the same way nothing may happen in this case also and let us wish for the same.
Otherwise we have to accept whatever happens, there is no way. Who are going suffer and who are going to withstand will be decided by time only.