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Though Pluto may no longer find a place in science textbooks as the ninth planet in our solar system — scientists have shrunk the number of planets to eight — it will surely be one of the most hotly debated and studied objects in the years to come. If 1930 marked the year when the 22-year-old Clyde Tombaugh discovered Pluto, August 24, 2006, saw the International Astronomical Union stripping it of its status as a planet. Incidentally, the same international body recognised it as a planet in 1930. The controversy But what in the first place prompted scientists to demote Pluto? The whole controversy started three years ago with the discovery of Xena by Michael Brown of the California Institute of Technology. "Had Xena's mass [and hence the lack of nearly round shape] and size been smaller, there would have been no problems," said Siraj Hasan, Director of the Bangalore based Indian Institute of Astrophysics (IIAP). Dr. Hasan represented India at the IAU meeting in Prague. That was not to be. "If Pluto can be a planet then why not Xena," he said about the controversy. One possibility was to enlarge the definition to include other objects including Xena. If that were so, there would have been 12 and not nine planets. And the possibility of more objects being found that would meet the criteria to be designated as planets is real, as the Kuiper Belt that lies beyond Neptune has many such objects; Pluto, like Xena, is one of the objects found in the Kuiper Belt. It was precisely this uncertainty that forced IAU to revisit the definition of a planet. "A panel of eminent planetary scientists was formed by IAU to get a proper perspective to decide the basis on which objects will be called as planets," Dr. Hasan said. "Finally consensus began to emerge. Because of the uncertainty in the number of objects that would meet the present criteria [of a planet], one more stringent criterion was added to the definition." Pluto, like Xena and other objects, met the first two conditions (orbiting the sun and being nearly round in shape) but failed to meet the new third criterion — clear the neighbourhood around its orbit. And Pluto lost out. Definition changed "They have just changed the definition [of planet]. It is more of a change in nomenclature," Dr. Hasan stressed, "not that we got new information about Pluto that made it no longer a planet." The reclassification does not in any way change whatever is already known about Pluto. Yet, some astronomers and others have not taken to its demotion kindly. "I do understand that many feel bad about it [the demotion of Pluto]," Dr. Hasan noted. While scientists will soon reconcile and see the basis on which Pluto has been called a dwarf planet, reactions of many laypersons have been more than sentimental. The very basis on which science works has now come under scrutiny. Many people with whom this correspondent talked had developed a cynical attitude towards science. Not dogmatic Alas, do people realise that science, unlike religion, is not dogmatic and any hypothesis is always open to scrutiny? "Science progresses by disproving hypotheses," underlined P.M. Bhargava, former Director of the Hyderabad based Centre for Cellular and Molecular Biology. "And in the method of science, when we do experiments to test a hypothesis, we design experiments that would disprove the hypothesis. And only when no further experiments can be done to disprove the hypothesis does the hypothesis become a fact." Science has no room for emotions and sentiments as well. "Methods of science are based on facts, observations, verification and validation," stressed Dr. Hasan. "Quite often, science progresses due to bold and imaginative hypotheses. The last step of verification involves subjecting the new hypothesis to further experimental scrutiny," said Dr. Baldev Raj, Director of Indira Gandhi Centre for Atomic Research, Kalpakkam. "There are many instances in science, such as discovery of the electron, when experimental observations were done much later in time; the hypothesis and theories were well accepted as the hypothesis explained the real life results in a coherent manner." Unlike other areas, science encourages dissent and differences of opinion. And repeatability (of experiments, methods, to name a few) is the cornerstone of science. "In science there is no objective truth," emphasised Dr. Bhargava. Only the `test of time' can make disproving certain things less likely to happen. As time passes and more knowledge is gained and no evidence is obtained to disprove a particular fact, the chances of disproving the fact keep decreasing. Curiosity and inquisitive nature seen in small children suddenly disappear when they grow up. Ever wondered why? "In the process of growing up, curiosity and inquisitive nature seen in small children are somehow discouraged," noted Dr. Raj. "The emphasis in the current education system should change from memory-based learning to facilitating creativity. And to increase and sustain the inherent scientific temper in children, we in the society must discourage those beliefs that are not based on science." And when scientific temper and inquisitive nature give way to emotions and sentiments, gullibility rears its head. Scientific temper But what in the first place is scientific temper? "It is a quality of observing the natural phenomenon and attempting a rational explanation based on existing knowledge or speculating a new explanation to be verified by further experimental and theoretical understanding," noted Dr. Raj. "Laws of science are universal. Science is an art of understanding nature." "When people lack scientific temper or enough patience to understand a phenomenon, they, in general, resort to calling it a miracle," said Dr. Raj. How else would it be possible to explain the mass hysteria and frenzy that was witnessed in 1995 and very recently when the `news' about Lord Ganesha `drinking milk' spread like wild fire. The fact that some people still believed in milk `miracles' and refused to see the scientific explanations became clear this time around too. Or take another recent `miracle' of seawater in Mahim Bay turning `sweet.' Luckily this time, the mass frenzy witnessed with the milk `miracle' was missing. Whether the scientific explanation offered or the police prevention of people from drinking the water played spoilsport is debatable. And `miracles' will continue to happen and people like Ramar Pillai who managed to hoodwink the scientific community and the lay public for some time, till IIT, Madras called his bluff, will surface time and again. "It is totally absurd," said Dr. Bhargava referring to Ramar Pillai's claim. "It defies all laws of chemistry, laws of conservation of mass and energy and laws of thermodynamics." Yet, Ramar Pillai was seen as God sent to help India have its own renewable source of `herbal petrol.' Unlike Ramar Pillai, Madonna, despite her celebrity status, had little luck. An article in Sunday Times (August 20) recounts Madonna and her husband's aborted efforts to convince the British Nuclear Fuels (BNFL) scientists on the ways of "neutralising dangerous nuclear waste in Ukraine" using the `magic' Kabbalah fluid. Many people who believe in these `miracles' take refugee in the argument that science has not been able to explain everything seen in today's world, let alone the past. True. What science has been able to discover and explain is only a fraction. That is no reason for certain phenomena that can indeed being explained be clubbed with those that science has still not managed to explain. That is also a reason why scientific temper is imperative to solve the many mysteries that nature offers. Quick Facts about Pluto Topic Data Diameter 2320 km Density 2.05 g/cm3 Mass 1.290 x 1022 kg Volume 6.545 x 109 km3 Temperature Range -240° C to -218° C Atmosphere Methane Winds Not Measurable Moons Three Average Distance from Sun 5,913,520,000 km Orbital Period 248 Years, 197 Days, 5.5 Hours Rotation 6 Days, 9.25 Hours Tilt 122.52° Rings None Composition Frozen Methane and Other Ices Magnetic Field None Pluto's origin and identity had long puzzled astronomers. One early hypothesis was that Pluto was an escaped moon of Neptune, knocked out of orbit by its largest current moon, Triton. This notion has been heavily criticised because Pluto never comes near Neptune in its orbit.[98] Pluto's true place in the Solar System began to reveal itself only in 1992, when astronomers found a population of small icy objects beyond Neptune that were similar to Pluto not only in orbit but also in size and composition. This trans-Neptunian population is believed to be the source of many short-period comets. Astronomers now believe Pluto to be the largest[note 9] member of the Kuiper belt, a somewhat stable ring of objects located between 30 and 50 AU from the Sun. Like other Kuiper belt objects (KBOs), Pluto shares features with comets; for example, the solar wind is gradually blowing Pluto's surface into space, in the manner of a comet.[99] If Pluto were placed as near to the Sun as Earth, it would develop a tail, as comets do.[100] Though Pluto is the largest of the Kuiper belt objects discovered so far, Neptune's moon Triton, which is slightly larger than Pluto, is similar to it both geologically and atmospherically, and is believed to be a captured Kuiper belt object.[101] Eris (see below) is also larger than Pluto but is not strictly considered a member of the Kuiper belt population. Rather, it is considered a member of a linked population called the scattered disc. A large number of Kuiper belt objects, like Pluto, possess a 3:2 orbital resonance with Neptune. KBOs with this orbital resonance are called "plutinos", after Pluto.[102] Like other members of the Kuiper belt, Pluto is thought to be a residual planetesimal; a component of the original protoplanetary disc around the Sun that failed to fully coalesce into a full-fledged planet. Most astronomers agree that Pluto owes its current position to a sudden migration undergone by Neptune early in the Solar System's formation. As Neptune migrated outward, it approached the objects in the proto-Kuiper belt, setting one in orbit around itself, which became its moon Triton, locking others into resonances and knocking others into chaotic orbits. The objects in the scattered disc, a dynamically unstable region beyond the Kuiper belt, are believed to have been placed in their current positions by interactions with Neptune's migrating resonances.[103] A 2004 computer model by Alessandro Morbidelli of the Observatoire de la Côte d'Azur in Nice suggested that the migration of Neptune into the Kuiper belt may have been triggered by the formation of a 1:2 resonance between Jupiter and Saturn, which created a gravitational push that propelled both Uranus and Neptune into higher orbits and caused them to switch places, ultimately doubling Neptune's distance from the Sun. The resultant expulsion of objects from the proto-Kuiper belt could also explain the Late Heavy Bombardment 600 million years after the Solar System's formation and the origin of Jupiter's Trojan asteroids.[104] It is possible that Pluto had a near-circular orbit about 33 AU from the Sun before Neptune's migration perturbed it into a resonant capture.[105] The Nice model requires that there were about a thousand Pluto-sized bodies in the original planetesimal disk; these may have included the bodies which became Triton and Eris.[