'Asteroids: space's new frontier'
-Navneet Kumar Gupta
For centuries man has wondered at the mysteries of outer space, trying to unravel them. Astronomical bodies such as satellites, stars, meteors, asteroids and comets have fascinated humankind and attracted them. Seeing some of these astronomical bodies, we either try to liken them in our imagination to some Divine Power or think of them as ‘falling stars’. Similarly, some say that our fates are linked to the movement of heavenly bodies. However, modern astronomy has rubbished quite a few of such myths. Today, we are much more informed about the realities of planets, satellites, comets and Black Holes.
Most of these astronomical bodies have their own peculiarities and properties. For instance, planets are heavenly bodies that orbit stars, such as our Sun, at a definite distance at definite speeds. The earth also has a fixed time to rotate around its own axis. This is what causes day and night. Likewise, planets have satellites that move around them, just like the moon does around the earth.
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Like the planets and their satellites, many meteors and comets move around in the solar system. These are essentially lumps of matter created out of gases, metals and rocks in the outer space. And they can be either minuscule in size or weigh lakhs of tonnes. The Italian astronomer Father Guiseppe Piazzi was the first to discover such astronomical matter on January 1, 1801. That was the discovery of Ceres, then thought of as a massive asteroid. However, later Ceres was declared as a Dwarf Planet. From then till now, more than 10,000 such asteroids and meteors have been found. Astronomers believe that these rotate around the sun in the belt between Mars and Jupiter, and in this belt, Ceres is the only Dwarf Planet. The distance of this belt is between 32 and 49 crore km from the sun.
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However, meteors and asteroids are also found in space apart from this belt. In 1961, the International Astronomical Organisation classified and termed these objects. They termed the independently moving bodies as meteors. These were, however, differing in size. Actually, these meteors are remnants of burnt-out comets or Planets. Sometimes these meteors go off their normal orbits and enter the atmosphere of the earth, moving at speeds of up to 30,000 km an hour. There are at least 5 to 10 meteor strikes on earth each year.
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The moment a meteor enters the earth’s atmosphere, pressure and friction on it cause it to burn up. We imagine such objects as falling stars.
Only recently, just such an event occurred in Vellore district, Tamil Nadu. This may be the first official confirmation of an object from space killing a living thing on earth this side of the 20th century.
While there have been claims earlier of meteorites proving fatal, including in the 20th century, there is no official confirmation of the same except for a cow that came under one in Venezuela in 1972, was struck dead, and quickly eaten. In 2007, the killer meteorite, which came to be used as a doorstop, was put up for auction. At the time, The Telegraph daily of the UK said the Valera meteorite fragment “holds the dubious distinction of being the only extra-terrestrial rock to have caused death”. The only confirmed human meteorite victim in history so far has been Ann Hodges, who was hit in her Alabama home in 1954 and survived. The most famous and researched incident involving meteorites in recent past was in Chelyabinsk in 2013.
In fact, the history of meteors is older than that of the earth for millions of years. It is said that when the age of this earth was one crore years, a massive meteor had smashed into it causing it to split into umpteen numbers of parts.
Besides, meteor strikes have been held responsible for the extinction of dinosaurs from the face of the earth. A massive meteor hit around 650 crore years ago had caused such a humungous volume of dust to spread into the sky that there was no sunlight for decades, which wiped out many animal species from the earth. But it is also a fact that out of every 5,000 such massive meteors, only one is likely to strike the earth. But such a hit can drastically alter the geography of the planet and ruin biodiversity. In fact, many of the large lakes on earth have been caused by meteor hits.
Approaching meteors can impact radio waves too. Among some of the important meteor strikes is the one at Peekskill, USA, in 1999. A meteor weighing around 12.4 kg had crashed into the land. In 2009, a meteor strike in Bali, Indonesia, caused a 10-metre crater to form there. The energy released by that meteor was around 50 kiloton, or twice more powerful than the Nagasaki atom bomb.
Meteors also shed valuable light on various other theories about space. Scientists study the presence of various forms of matter or elements in the outer space from the dust and rock pieces of the meteors. And the latest meteor strike has warned astronomers to remain alert and try to assess the next time when such an event might recur so that safety measures are taken in advance.
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Navneet Kumar Gupta is a science communicator working as a Project Officer (Edusat) in Vigyan Prasar-National institute of Science communication under the Department. of Science & Technology. Govt. Of India. He has a deep interest in popular science writing for the general public through Print and electronic media. Besides his twelve books, he has written more than 200 popular science articles. He has edited/authored/co-authored more than 10 books. He have been awarded six National Awards including Rajbhasha Award, Ministry of Home Affairs, Government of India He has had a long stint as Associate Editor, VIPNET news - a popular science magazine. You may contact him at - ngupta@vigyanprasar.gov.in