Leonid storm is no light matter
The last Leonid storm, in 1966, did not evoke so much interest, for only a few spacecraft were in orbit. The parent comet Tempel-Tuttle reached perihelion (point nearest the Sun) on 28 February, 1998, precipitating a meteoroid shower through which the Earth and about 500 operational satellites (6 per cent of the total of 8000 in orbit) will plough.

Cybersurfing with Amar Chandel
Virtual art galleries
Making good paintings is only half the battle won. Getting them well displayed comes in the other half. Booking art galleries and paying their hefty charges has frustrated many a promising artist. Enter the Internet. Many websites have started exhibiting art works. But the problem is that most of them are commercial sites charging hefty fees to display one’s works.

Web software for the blind
IBM researchers have developed a software that will help blind people read text on the World Wide Web (WWW) over Internet.

Your home and pollution
by A. P. S. Kaleka
THINK pollution and you think of smokes emanating from factories and dusty roads. We scream ourselves hoarse about how advances in technology have ruined the environment, and our health too. But do you know that your own home offers no better a situation!

Science Quiz
by J. P. Garg

Cosmic fireworks & orbiting spacecraft
by Pravin Kumar

ON a clear night, well away from city lights, you will most probably see bright streaks of light across the sky, at the rate of four or five in an hour. These are popularly called “shooting stars” or meteors-extra-terrestrial debris ranging in weight from 0.1 gm to a few kilograms. Travelling at 72-km per second, they get heated and vaporised. The light is due to the heat generated by friction with air and to the ionisation of air molecules.

Meteors become visible at heights of around 190 km and get burnt out before they drop below 80 km. The brightest meteors may outshine the full Moon and are then termed “fireballs”. Occasionally the sound of their passage can be heard. Meteors which explode are called “bolides”. Those projectiles which are big enough to survive the fiery passage through the Earth’s atmosphere and impact the Earth in the form of rocks are called “meteorites”. In addition, there are smaller particles with diameter of 5/1000 inch which have no luminous effect; these are called “micro-meteorites”. They are also different in composition from the bigger meteorites. Collectively, these visitors from space are called “meteoroids”.

The outsize meteorites make a large crater when they hit the Earth. A famous example is the Great Meteor Crater (strictly, it should be ‘Meteorite Crater’) in Arizona (USA); this was produced by a meteorite that hit about 20,000 years ago. Lonar Lake in Buldana district, Maharashtra, is also believed to represent the site of a meteorite hit.

Mostly, meteors are sporadic and travel round the Sun in elliptical orbits. They may appear at any moment and from any part of the sky. Those that travel in shoals are the “shower meteors” that are responsible for spectacular displays, often at specific times of the year. Due to the laws of perspective, these appear to arrive from a particular point in the sky (the “radiant”) just as parallel lanes on a highway, or railway lines, will seem to radiate from a point near the horizon.

Meteor showers are generally named after the stellar constellation that contains the radiant. Thus, the Perseids, which occur from July 23 to August 15 every year, radiate from Perseus. When two or more showers have radiants in the same constellation, they are named after a nearby bright star, e.g., the Eta Aquarids. Several showers are named after the comet from which they are derived.

The richness of the shower is given by the Zenith Hourly Rate (ZHR); this is the number of naked-eye meteors expected to be seen by an observer with the radiant at the zenith or overhead point. The actual rate may be less than the theoretical rate. When the number of meteors is high, it is called a “meteoric storm”.

Meteorites are derived from asteroids in the asteroid belt, between Mars and Jupiter; in fact, asteroids like those belonging to the Amor and Apollo group have orbits crossing Earth’s Meteors, on the other hand, originate from short-period comets with periods of less than 200 years. As a comet nears the Sun, the material of its nucleus breaks off due to solar radiation and heating, as well as pressure effects. The particles which separate from the comet go into an orbit corresponding to the parent comet’s orbit. Over time, gravitational and other effects distribute the material more uniformly around the orbit. When the Earth’s orbit intersects the orbit of the debris we see “shower meteors”.

Comet Halley, which visits the Earth every 75 years, on an average, is linked with two showers, the Eta Aquarids (5 May) and the Orionida (21 October); these may contain 10 times the total mass of the comet nucleus, which gets whittled down every round trip. However, due to perturbations by the giant planet Jupiter, a comet as well as its meteoroid stream may cease to intersect the Earth’s orbit in the future. On the other hand, some meteor streams have intersected the Earth’s orbit for hundreds of years. The Lyrids were first recorded in 687 BC and the Leonids in A 902.

Biela’s comet
The connection between comets and meteoroids is clear from the case of Biela’s comet. Discovered in 1826 by Wilhelm von Biela, it was calculated to return in 6¾ years. It was just visible in 1832 but was missed on its return in 1839 because it was badly placed in the sky. On its return in 1845 it had split into two parts, which reappeared in 1852. It failed to appear in 1866, when it was due, but in 1872, when it was due again, a brilliant shower of meteors showed up in the part of the sky where it was expected. There was another display in 1884, but none after that.

The Leonid showers, which get their name from the constellation Leo, are coming this week (with a peak at 2.10 a.m. on November 18). The meteors are bunched up, instead of being spread all round the orbit, so the best displays occur every 33 years, when Comet Tempel-Tuttle (period, 32.9 years) is close in. In 1866, the display was so spectacular that snowflakes seemed to be falling from the sky for four hours. The next display was due in 1899, but, due to planetary perturbations, the main cluster was missed. The 1966 return of the Leonids was the greatest celestial show of the century, the ZHR reaching 100,000 in Arizona (USA). This month’s display could be scintillating, predicts the celebrated astronomer Patrick Moore in his book The Amateur Astronomer.

Risk to spacecraft
Earthlings have little to fear from these celestial missiles, because few survive their fiery passage through the Earth’s atmosphere. But these small, highvelocity objects in near-Earth space are scaring space missions and spacecraft designers. The launch of the spacecraft Discovery was delayed in August, 1993, due to the Perseid showers which occur in that month. Right now, preparations are under way to protect the 500-odd Earth-orbiting satellites from the Leonid fusillade of 500 to 10,000 meteors per second, whizzing at 72 km per second.

Some communication companies believe that the Leonid showers will damage every second satellite. When a dust particle hits a satellite, matter burns up, causing an electrical discharge which will damage the satellite’s on-board computers. To prevent damage, the Hubble Space Telescope’s expensive mirrors are being turned to minimise the chances of their being hit by meteoric dust. According to the Indian Space Research Organisation’s (ISRO) release, the probability of the five INSAT satellites and the four IRS satellites being hit is 0.01 to 0.03 per cent. The solar panels of the satellites, which generate electricity from photo-voltaic cells, will be turned in such a way as to present the smallest surface to the oncoming meteoroids.

Because of the risk to spacecraft from meteoroids, attempts have been made to measure their flux in space by means of HEOS, Helios and Pioneer spacecraft. Micro-meteorite collectors have been deployed from the MIR space station and are planned for the Space Station Freedom, to be launched in December 1998.

Apart from the threat to spacecraft, meteoroids are of interest because, being the oldest material objects on Earth, their origin may throw light on the evolution of the early Solar System. Some contain even older grains that may have survived unaltered since their formation near other stars. Their varying composition suggests that they are from many sources; hence, they provide samples of dozens of different solar system bodies.

Broadly, meteoroids are of two types stones (aerolites) and irons (siderites). These rocks provide detailed information on mineral structure and elemental composition which telescopes and aircraft cannot provide. Last year, scientists at Arizona State University (USA) found large amounts of left-handed aminoacids in the Murchison meteorite which landed in 1969 in Australia. Amino-acids are the building-blocks of proteins and are fundamental to organisms, but their discovery in the meteorite means that one-handed organic molecules predate life and might have been present in the material from which the solar system grew.

Leonid storm is no light matter

The last Leonid storm, in 1966, did not evoke so much interest, for only a few spacecraft were in orbit. The parent comet Tempel-Tuttle reached perihelion (point nearest the Sun) on 28 February, 1998, precipitating a meteoroid shower through which the Earth and about 500 operational satellites (6 per cent of the total of 8000 in orbit) will plough.

In a paper published in Current Science journal Dr T Parimala Rangan and associates from ISRO Telemetry Tracking and Command Network, Bangalore, have worked out the combined effect of factors like the impact probability, the relative velocity of the meteoroids, orientation of the spacecraft to meteoroids, etc., upon which will depend the damage suffered by the satellites. Their analysis indicates that “all Indian satellites serving scientific, communications and remote sensing missions are certain to undergo this ordeal... and Earth will not protect the satellites as the orbital planes will be exposed to the storm” (which lasts about five hours.) Though the impact probability for Indian satellites is low, an actual impact could be catastrophic.

The meteoroids could damage satellites or their components, cause pitting of optical surfaces and mirrors, though physical damage to the solar panels is unlikely as the meteoroid storm will approach edge-on to the sun-tracking solar panels.
— P. K.

Cybersurfing with Amar Chandel
Virtual art galleries

Making good paintings is only half the battle won. Getting them well displayed comes in the other half. Booking art galleries and paying their hefty charges has frustrated many a promising artist. Enter the Internet. Many websites have started exhibiting art works. But the problem is that most of them are commercial sites charging hefty fees to display one’s works.

But at the same time, there are quite a few non-commercial websites that show artworks exclusively of their liking but without charging any money. The Garret Gallery is one of them which is run by a well-known art collector, Mr Drummond Mile, who is based in Mumbai. It can be accessed at www.gadnet.com/garretm.htm. Incidentally, for this month, it has chosen Chandigarh’s very own Balvinder for display. He is perhaps the first artist from the region to be thus honoured.

Another art gallery worth frequenting is at www.chitrakoot.com. It features several artistes such as Ganesh Haloi, Manoj Dutta and Sanat Kar.

Those with a poetic bent of mind should try out freespace.virgin.net for downloading a sort of notepad-cum-thesaurus. The Random Verse Lab (RVL) software can help them write poetry. One can create one’s own templates by specifying where one wants verbs, nouns etc to appear. After that, the software take over. The results may not be very flattering but those are your own creations, after all.

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There are search engines and search engines. Everyone has his or her own favourites. I stumbled on one which combines the strength of all of them. Ask it to search something and it utilises the combined capacity of several search engines to come up with a vast list of results. It has been appropriately christened www.mamma.com. Like a true traditional mamma, it goes to considerable pains for you. Try it out. Particularly helpful are sites on fun and entertainment.

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And here is something which may warm the hearts of women. Here is a whole site (www.queendom.com) to help them improve their personality. There are numerous personality tests, intelligence tests, tips on attitudes, lifestyle and emotional health. Then there are brain teasers and puzzles which put you on your way to natural leadership.

Men can take heart. Although the main chunk is devoted to women, there are any number of helpful hints for men as well. In any case, all those tips that are good for the fair sex are good for them as well, no?

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Like it, dislike it, debunk it ... but you cannot ignore astrology. It has as many diehard supporters as it has cynics. For the former, one recommendable site is www.astrology-online.com which gives you your overall as well as time-specific predictions in a jiffy. One can also learn quite a bit about astrology through various sections and also surf on to various other links.

Web software for the blind

IBM researchers have developed a software that will help blind people read text on the World Wide Web (WWW) over Internet.

The software, developed by researchers at IBM’s Tokyo Research Laboratory, is available in Japanese and an English version is under way, reports IBM Research.

It is inspired by IBM’s Screen Reader TM 2, which can enable blind persons to access the Netscape Navigator TM Web browser. The problem is that the software reads text-based information only, and is therefore, not suited to the Internet’s multimedia environment, which contains embedded images and hyperlinks.

The new software is capable of interpreting the Wed’s special coding. One of the biggest challenges, according to team leader Chieko Asakawa, was devising a simply way to navigate as blind people can not use the mouse.

The solution was to use the computer’s numeric keypad. Once online, the package called Homepage Reader announces the default home page, and the surfer can use a number of keys to move between pages, lines and individual characters. If the user wants to read something, he just double-clicks key 2 and the system reads the page from the beginning. Other keys let the user fast-forward, rewind or jump to the next link on the page. When the reader arrives at a hyperlink (a piece of text or graphics in a document which when clicked takes one to a related web site), the voice switches from male to female — a cue that Asakawa deems “intuitive and natural.”

Your home and pollution
by A. P. S. Kaleka

THINK pollution and you think of smokes emanating from factories and dusty roads. We scream ourselves hoarse about how advances in technology have ruined the environment, and our health too. But do you know that your own home offers no better a situation!

Lots of people, who suffer from sneezing, bronchitis, minor coughs, eye irritations would be surprised to know that the source of their irritation is lurking in their own homes. Check out the hidden sources of pollution and what you can do to control them.

1. Air Freshners of your room: Solid deodorisers release paraperidichloro benzene, a chemical that is suspected to cause cancer, as they melt into the air. Allergeologists say that the best way to freshen your rooms is to keep them well-ventilated. Allow fresh air to move freely in and out of the house.

2. Beating the mosquito menace: Mosquito repellants emit smoke and along with it they also release a chemical which which leads to bronchial problems and pharyngitis. The best method of coping with the mosquito menace is to use meshes on windows or bed-nets.

3. Cigarette smoking is dangerous to health: Cigarette smoke gives both the smoker and everyone else in the house an unhealthy dose of more than 4000 chemicals. Second had smoke can irritate your eyes, nose and throat and it may even lead to lung cancer. So take a hard line against smoking in your home.

4. Vent out agarbatti fumes: The incense sticks you light in your home could irritate the respiratory system of asthmatics. So when you light them, don’t overdo it and make sure that the room is well ventilated to allow the fumes to go out.

5. Back out the car: Gasoline engine exhaust is a deadly source of carbon monoxide. So do not let your auto run in idle in an attached garage.

6. Air out dry-cleaned clothes: The chemical used to dry-clean your clothes i.e. tetrachloro ethylene, has been known to cause cancer in animals and could as well cause cancer in humans, too. Airing out of these clothes before storage to cut pollution levels is advised.

7. Clean, clean bathroom: Everyone likes clean bathroom, but be careful while using toilet cleaners. The chemical phenol that is released is known to cause shortness of breath and sneezing.

8. Can plants reduce pollution levels: Some plants like neem and tulsi and also bamboo palm, chrysanthemums and ferns, have been known to clear the air. But there is also a warning. Don’t overdo it. Too many plants can cause breathlessness. Besides, plants give out carbondioxide at night, so when the sun goes down, put your plants outside.

Science Quiz
by J. P. Garg

1. Name the internationally recognised entrepreneur and agricultural expert Indian farmer who has recently been awarded this year’s World Food Prize for promoting private enterprise in India’s agriculture sector. To which state does he belong?

2. Some farmers of Maharashtra have developed a wonder manure which, they claim, can help grow bumper crops of vegetables, fruits and trees. What has this manure been named? In addition to having cow dung and groundnut cake as its main ingredients, which three chemical fertilisers are used in preparing this manure?

3. ENG refers to a process related to the production of newspapers. What does ENG stand for?

4. Roslin Institute of Scotland which cloned the sheep Dolly has been accused of pirating a gene from a rare and nearly extinct dwarf breed of cattle only found in Kerala. Which is this cattle breed and what is special about it?

5. Garlic is known for its medicinal properties. A potent antibiotic drug is extracted especially from garlic. Name this drug.

6. The blood of an insect which has green body and eats green leaves of plants is white in colour. This insect can be seen in house gardens. Name this insect.

7. “Snowball”, “Spider”, “Pompon”, “Spoon” and “Reflexed” are only a few of hundreds of varieties of this delicate, multi-coloured and magnificent flower that blooms in November and December. Which family of flowers are we talking about?

8. North India will soon have a highly sophisticated giant telescope that would enable astronomers to view the entire universe up to its edge and would use solar energy for generating power for its functioning. Where is it being set up?

9. Suggest one word for “the use of electrical signals to transmit medical information with a view to overcoming the barriers of time and distance.”

10. Name the city of India that is fast becoming the industrial hub of information technology and has come to be known as “Cyberbad”.

Answers
1. Badrinarayan Ramulal Barwale; Maharashtra 2. “Amrit Sanjivani”; urea, superphosphate and potash 3. Electronic News Gathering 4. Vechur, the smallest cattle breed in the world famous for the high fat content in its milk that exceeds that of European cattle 5. Allicin 6. Grasshopper 7. Chrysanthemum 8. At Hanlee near Leh in Ladakh 9. Telemedicine 10. Hyderabad.

Matchbox-size heater
Using an array of sophisticated technologies, Russian researchers have come up with electric heaters that can even be fitted into a matchbox.

The new electric polymer heaters have been developed by scientists at the Central Special Machine Building Research Institute, reports Ria Novosti.

The heaters are available in varying sizes and shapes — from single panel to folding screen types — to produce temperatures of as low as 30 degrees Celsius to as high as 130 degrees Celsius.

One of the most important advantages of the heater is its high efficiency compared to conventional heaters. Besides, it reproduces optimal heat without any adverse effects, does not require additional heat screens and does not consume oxygen present in the room.

Manufactured by the Moscow-based Eksition NEP Firm, the heater is made of a monolith fibre plastic plate that houses a fibre-glass heater.

The heater is soaked with a soot-graphite mixture to which electrodes are attached.

Flat television screens
Full-sized and flat colour television (CTV) screens made of plastic will be shortly produced by Cambridge Display Technology (CDT) of UK in collaboration with the Japanese electronics giant Seiko-Epson.

The small screen has the potential to be used in portable video cassette recorders (VCRs) and digital cameras. The colour screen will provide thin and flat screen for TV and computer monitors.

The technology that can eclipse cathode ray tubes in the next generation of computers, television and mini-display screens, has a number of applications ranging from low-information alphanumeric displays on mobile telephones or VCRs to sophisticated full-colour flat-panel displays.

Philips has announced the commercialisation of the technology for back-lit number displays in mobile telephones and possibly other applications, reports London Press Service.

A 50-millimetres (mm) square prototype of two-millimetres thickness showing high definition black and white TV has already been produced. Unlike a liquid crystal diode, it has no restriction on viewing angles and no blurring of fast moving pictures.

Mystery of Jupiter’s rings solved
US astronomers have discovered the origin of the planet Jupiter’s rings — including one described as a hula-hoop wobbling around its “fat waist”, reports Reuters.

In what is hailed as a major find, they said the three rings consisted of tiny dust particles kicked up by space rocks hitting Jupiter’s four inner moons and dragged into orbit around the solar system’s largest planet.

Jupiter’s rings, unlike the famous ones around the planet Saturn, cannot be seen from Earth. They were only detected by the Voyager-1 spacecraft in 1979 and their origins have been a puzzle to scientists ever since.

Astronomers had theorised the rings might be composed of dust particles. But they had no real proof until the astronomers, from Cornell University in New York, analysed images and data sent back to Earth by the space probe Galileo, which has been orbiting the planet for more than two years.

Jupiter’s moons, Metis, Adrastea, Amalthea and Thebe, were constantly being “pelted by storms of comets and asteroids travelling at 40 kilometres a second, which is 100 times the speed of a 10.22 calibre bullet”, they said.

Thousands of dust particles were thrown up with each collision, Cornell University scientist Joe Veverka said. Because the small moons had very little gravity, the particles were dragged into the planet’s gravity, forming the rings.

It was also discovered that the rings “wobble” with the orbits of the four moons. Veverka described the outer ring, known as a gossamer ring, as “a hula hoop around Jupiter’s fat waist. “The rings stretched for about 240,000 km out from Jupiter but the dust particles were very thinly spread, each being about 27 metres from the other, Veverka added.

The rings never increased in size or density because the tiny particles that formed them had a limited lifespan and were constantly being replaced by fresh particles.

The scientists said the brighter of the three rings was the main ring, which also had a halo. The two outer rings are known as gossamer rings. Each ring is defind by the orbit of its “feeder planet.”

Intelligent antennae
Researchers in Germany have come up with a new “intelligent antenna” that can enhance capacity of mobile telephone networks.

As mobile telephone network operators are allocated only a limited number of transmission frequencies, their network capacity will at some point be too small to guarantee operation without interference if the conventional antennae and transmission densities are struck to.

Every mobile telephone user currently requires a channel, i.e. a frequency, at a certain point in time in the transmission area during which operators in the neighbouring cells have to block entrance to this frequency to prevent interferences and confusion in overlapping parts of the transmission area.

Instead of transmitting for a user at one frequency throughout the entire area of the cell and blocking it for the entire cell, intelligent antenna enables the same frequency to be accessible for several users in various areas of the cell. The antenna first of all delects the participant and continues to follow him or her during reception.