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| SCIENCE & TECHNOLOGY |
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Rare
transit of Venus Road
markings with glass beads!
UNDERSTANDING THE
UNIVERSE
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Rare transit of Venus This account is a unique example of the rarity and importance of certain astronomical events and the perseverance required on the part of an enthusiast. No one alive today has seen the transit of Venus, as it is occurring for the first time in 121 years. Actually, the transits come in cycles of 243 years as well as in series (1761/2004, 1769/2012, 1874/2117, 1882/2125). So, when one transit takes place, the next one in the pair comes eight years later, in the same month, which is either June or December. The last pair had occurred in Dec. 1874/1882. This year, the transit will start on June 8th at 10:46 IST, when the limb of Venus touches that of the sun (first contact), thus beginning ingress. The second contact occurs 20 minutes later, whereupon the whole of Venus can be seen as a black disk in front of the sun. The egress begins with third contact at 16:31, ending the transit at 16:50. In earlier times, such transients were useful in calculating our distance from the sun by measuring solar parallax. This is achieved by finding the small difference in contact timings at widely separated places. Students can take up this experiment as a learning exercise. Other interesting observations include watching the crescent Venus a few days before and after the transit. Due to scattering in the upper layers of Venus’s atmosphere, the horns of the crescent get faintly extended, sometimes forming a complete circle. This phenomenon was the first evidence that Venus had an atmosphere. During the ingress and egress, the refraction of sunlight in the upper layers of Venusian atmosphere causes a bright aureole surrounding the dark limb of the planet. This has never been photographed so far and is known only from the written accounts of previous observers. The transit can be observed through binoculars or a small telescope by placing a solar filter (e.g. Mylar) in front of the instrument. It is much safer to use the eyepiece projection method for indirect viewing. Care should be taken that the telescope's secondary mirror or eyepiece do not get overheated due to long exposures or as a result of sharp, focused beam of light falling on some black casing etc. It would be worthwhile trying to take pictures of the transit, especially the aureole during ingress and egress. |
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Road markings with glass beads! Another important factor is to ensure visibility of road markings during night time. In general, this aspect is not paid due attention. Mostly, adequate light is available at the crossings but not along the routes. It is not possible to provide fluorescent paint markings all along the road lengths because of cost restraints and high glare problems. Fluorescent paint glare may sometimes blind the vehicle drivers resulting in their losing the balance and causing mishaps. To overcome the problem, a new product has been invented and now, it is available in India also. It is a cold plastic coating material that gets hardened through a chemical reaction and serves as a permanent marking paint. This cold setting marking paint is thixotropic and carries refractive glass beads in it which shine during night without causing any glare to the drivers and make the markings visible during night. The paint hardens within 20 to 30 minutes of its application and thus can be used without much hindrance to road traffic. Produced in both the colours used for roads i.e. white and yellow, it has two components which are mixed and stirred well before applying. As the setting time of the mixed paint is 20 minutes, the mixture need to be used within this period. Thus machine marking is preferred over manual marking for better efficiency, good and accurate marks and optimum coverage. Coverage capacity is quite good, consumption ranging between 1.5 and 2.0 kg per sq.metre per mm thickness. The paint is weather resistant, skid resistant and tested for day and night visibility. White paint has the properties of non-yellowing and oil spill resistance also. The road marking machine produced to apply this paint carries an Auto Glass Bead Application system. If the machine capacity is 75 kg, the glass bead container has a corresponding capacity of 10 kg. However the flow of glass beads can be increased or decreased through a knob provided for the purpose. Glass beads application activates automatically as soon as paint application begins. The bead container has a level indicator which ensures addition of more quantity of beads to the container well in time. The machine is quite cheap and proves economical than manual painting. Modern cities like Chandigarh should try such markings on one or two roads. Further use can be made after assessing the performance of glass bead paint markings, if found satisfactory. |
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UNDERSTANDING THE UNIVERSE On
what basis do scientists claim that life may be possible on Mars? Have they found any evidence such as remnant of plants or any other life forms? If we look at other planets of our solar system we do not find many good candidates. Moon is too small and cannot have an atmosphere. Mercury is horribly hot and cold during its days and nights, and cratered much like our moon because it lacks the protection of an atmosphere. Venus seems to have done something wrong during its evolution. It is subject to a runaway greenhouse effect, raising it temperature to hundreds of degrees Celsius. Jupiter is enormous, has a thick atmosphere, with its lower parts at thousands of degrees, altogether uncongenial from the point of an earth-bound scientist even when he would grant a latitude of few hundred degrees Celsius for survival of
life if it did develop. Moons of Jupiter like Europa are beginning to look attractive because they might have pools of liquid water. Mars, on the other hand seems like an attractive candidate. There is evidence that it did have flowing water at some time. It probably still has some frozen below the surface. Its atmosphere is thin, but might not be completely hopeless. We certainly cannot expects elephants, monkeys or men running around there but some attempts to begin life would be useful and extremely instructive. Because of all these reasons I am very partial towards scientists who are spending enormous effort to detect any positive evidence of life processes on Mars. Our solar system itself is a tiny part of the universe. We could go on looking for evidence of life having emerged somewhere or the other. Some searches have been made but we have not looked enough. Did the astronauts come across any disease causing organisms while in space? I cannot give a categorical answer to this question. On the other hand some could say that going a few hundred kilometers away from the earth still keeps you closer to the bacteria of the earth. You could also say, as some astronomers have contended, that you cannot rule out the fact that some of the viruses and bacteria on earth might have an interplanetary, even interstellar, origin. The earth does provide a hospitable home to many forms of life that might or might not be good for us. That it provides the only origin for them cannot yet be proved. |
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Flexible E-paper A US company developed the electronic ink over the past several years. “Just like your newspaper, you can see it in bright light, dim light, or from all angles,” says Michael McCreary of E Ink in Cambridge, Mass. The ink consists of millions of microcapsules, each one containing white and black pigments of opposite charge. When a certain voltage is applied, the white pigments rise to the surface and the black ones descend out of sight. An opposite voltage leads to black pigments on top. Each pixel in the display is controlled by its own silicon-based transistor. Virtual nanotech It’s hard enough to thread a needle. Imagine trying to manipulate threads and needles miniaturised to one-millionth the normal size. Now, you’re thinking like the emerging group of nanotechnologists whose growing dexterity at fashioning new materials and devices may eventually improve every arena of technology, from aerospace to drug development. While many researchers focus on developing tools for working on nanoscale materials, others are pursuing a virtual pathway toward nanotechnology applications. |
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No, scientists have not found any evidence for remnants of plants, animals or other significant life forms. But search for life beyond the earth is a natural urge. It is true that our earth is a wonderful planet but it is only a tiny little rock around an ordinary star. There are billions upon billions such stars in the universe. Even if life is an extremely rare and wondrous natural happening, surely it could have found a foothold at some other places. One finds that organic molecules of the type used by life forms are found in abundance in many molecular clouds in our own galactic development. If life is not a unique miracle but a natural outcome of far from equilibrium thermodynamics in the evolution of matter and energy, one cannot stop looking for its growth in all sorts of near congenial locations. 
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