a collection of my published and unpublished articles

Saturday, November 1, 2008


Sir Arthur Charles Clarke, is a writer, under-water explorer, science popularizer and futurist, - the last surviving member of what was sometimes known as the “Big Three” of science fiction, which included Robert A. Heinlein and Isaac Asimov. He completes his 90th orbit today, December 16, 2007.

The achievements of Arthur C. Clarke, unique among his peers, bridge the arts and sciences. His works and his authorship have ranged from scientific discovery to science fiction, from technical application to entertainment, and have made a global impact on the lives of present and future generations.

Arthur C. Clarke is the son of an English farming family, born in the seaside town of Minehead, Somerset, England on December 16, 1917. As a young boy, he enjoyed star gazing and reading old American science-fiction pulp magazines. After secondary school and studying at Huish’s Grammar School, Taunton, he was unable to afford a university education, and then he moved to London in 1936, and pursued his early interest in space sciences by joining the British Interplanetary Society. There he started to experiment with astronautic material in the BIS, contributed to the BIS Bulletin, and began to write science fiction.

As with so many young men at the time, when World War II started in 1939, he joined the Royal Air Force, eventually becoming an officer in charge of the first radar talk-down equipment. He was involved in the early warning radar defence system which contributed to the RAF’s success during the Battle of Britain. Clarke actually spent most of his service time working on Ground Controlled Approach (GCA) radar. Although GCA did not see much practical use in the war, after several more years of development it was vital to the Berlin Airlift of 1948-1949. He was demobilised with the rank of Flight Lieutenant.
Later, his only non-science-fiction novel, Glide Path, was based on this work. 

After the war, he returned to London and to the BIS, becoming its president in 1947-50 and again in 1953. 
His most important contribution - geostationary satellites, would be ideal telecommunications relays. He was the first in the world to propose this concept, doing so in a paper privately circulated among the core technical members of the BIS in 1945. The concept later was published in a UK periodical magazine, Wireless World in October of that year as a technical paper “Extra-terrestrial Relays” laying down the principles of the satellite communication with satellites in geostationary orbits - a speculation realised 25 years later. 

During the evolution of his discovery, he worked with scientists and engineers in the USA, in the development of spacecraft and launch systems, and addressed the United Nations during their deliberations on the, ‘Peaceful Uses of Outer Space’. His invention has brought him numerous honours, such as the 1982 Marconi International Fellowship, a gold medal of the Franklin Institute, the Vikram Sarabhai Professorship of the Physical Research Laboratory, Ahmedabad, the Lindbergh Award and a Fellowship of King’s College, London. Today, the geostationary orbit at 42,000 kilometres is named The Clarke Orbit by the International Astronomical Union.

After leaving the RAF in 1946, he resumed his formal studies and was awarded a Fellowship at King’s College, London where he obtained first class honors in Physics and Mathematics in 1948. 

While Clarke had a few stories published in “Fanzines” between 1937 and 1945, his first professional sales appeared in Astounding Science Fiction in 1946: “Loophole” was published in April. The first story Clarke sold professionally was “Rescue Party”, written in March 1945 and appearing in Astounding Science in May 1946. Along with his writing, Clarke briefly worked as Assistant Editor of Science Abstracts (1949) and also contributed to the Dan Dare series. 

Thereafter he devoted himself to writing full-time from 1951 onward. He went on to become a prolific writer of science fiction, renowned worldwide and with more than 70 titles to his name. Among his many non-fiction works, “Profiles of the Future” (1962) looked at the probable shape of tomorrow’s world and stated his “Three Laws”.

In 1948, he wrote “The Sentinel” for a BBC competition. Though the story was rejected, it changed the course of Clarke’s career. Not only was it the basis for A Space Odyssey, but “The Sentinel” also introduced a more mystical and cosmic element to Clarke’s work. Many of Clarke’s later works feature a technologically advanced but prejudiced mankind being confronted by a superior alien intelligence. In the cases of The City and the Stars, Childhood’s End, and the 2001 series, this encounter produces a conceptual breakthrough that accelerates humanity into the next stage of its evolution.

He met and quickly married Marilyn Mayfield, an American, on June 15, 1953. They split in December 1953, although the divorce was not finalized until 1964. As Clarke says, “The marriage was incompatible from the beginning. It was sufficient proof that I wasn’t the marrying type, although I think everybody should marry once”.

In 1954, Clarke wrote to Dr. Harry Wexler, then chief of the Scientific Services Division, U.S. Weather Bureau, about satellite applications for weather forecasting. From these communications, a new branch of meteorology was born, and Dr. Wexler became the driving force in using rockets and satellites for meteorological research and operations.

Clarke first visited Colombo, Sri Lanka (at the time called Ceylon) in December 1954 and started to give up his interest in space, for the ocean. About the reasons, he said: “I now realise that it was my interest in astronautics that led me to the ocean. Both involve exploration, of course - but that’s not the only reason. When the first skin-diving equipment started to appear in the late 1940s, I suddenly realized that here was a cheap and simple way of imitating one of the most magical aspects of spaceflight - weightlessness.”

Clarke has lived in Sri Lanka since 1956, first in Unawatuna on the south coast, and then in Colombo. He has long been an avid scuba diver and a member of the Underwater Explorers Club. Living in Sri Lanka also afforded him the opportunity to visit the ocean year-round. It also inspired the locale for his novel The Fountains of Paradise, in which he first described a space elevator. This, he believes, ultimately will be his legacy, more so than geostationary satellites, once space elevators make space shuttles obsolete.

In 1959, with his colleague/friend, late Herschel Gunewardena, he founded the Ceylon Astronomical Association (now known as Sri Lanka Astronomical Association). Through the Association, Clarke and his colleuges did a tremendous amount of work to improve sceince-astronomy in Sri Lanka.

In 1964, he started to work with the noted film producer Stanley Kubrick on a science fiction movie script. As the idea developed, it was decided that the story for the film was to be loosely based on Clarke’s short story The Sentinel, written in 1948 as an entry in a BBC short story competition. Originally, Clarke was going to write the screenplay for the film, but this proved to be more tedious than he had estimated. Instead, Kubrick and Clarke decided it would be best to write a novel first and then adapt it for the film upon its completion. However, as Clarke was finishing the book, the screenplay was also being written simultaneously.

Four years later, he shared an Oscar nomination with Kubrick at the Hollywood Academy Awards for the film version of “2001: A Space Odyssey”. Then, in 1985, he published a sequel, “2010: Odyssey Two” and worked with Peter Hyams on the movie version. Their work was done using a Kaypro computer and a modem, linking Arthur in Sri Lanka and Peter Hyams in Los Angeles, leading to a book “The Odyssey File - The Making of 2010.” 

In television, Clarke worked alongside Walter Cronkite and Wally Schirra for the CBS coverage of the Apollo 12 and 15 space missions. His thirteen-part TV series Arthur C. Clarke’s Mysterious World in 1981 and Arthur C. Clarke’s World of Strange Powers in 1984 has now been screened in many countries. He made part of other TV series about space, such as Walter Cronkite’s Universe series in 1981.

In 1988, he was diagnosed with post-polio syndrome and since, has needed to use a wheelchair most of the time. On 10 September 2007, while commenting on the Cassini probe’s Flyby of Iapetus, Clarke mentioned that he now is completely wheelchair-bound by polio, and does not plan to leave Sri Lanka again. But as he says, quote- “ Being completely wheel-chaired doesn’t stop my mind from roaming the universe – on the contrary!”

In early 1998, with Prince Charles visiting Sri Lanka in order to make the investiture, Clarke was scheduled to be made a knight. During this time – just before the ceremony took place- a British tabloid, The Sunday Mirror, claimed in a sensationalist story that Clarke was an avowed paedophile, giving supposed quotations from Clarke about the harmlessness of his predilection for boys. Clarke released a statement saying that, “the accusations are such nonsense that I have found it difficult to treat them with the contempt that they deserve.” He also added, “I categorically state that The Sunday Mirror’s article is grossly defamatory and contains statements which in themselves and by innuendo are quite false, grossly inaccurate and extremely harmful.” He later asked that the investiture of his knighthood be delayed, “in order to avoid embarrassment to His Royal Highness the Prince of Wales during his visit to Sri Lanka.” In answer to the newspaper’s allegations, Clarke was investigated by Sri Lankan authorities, who eventually dismissed the accusations. The Sunday Mirror later printed a retraction and Clarke was made a Knight Bachelor on May 26, 2000, in a ceremony in Colombo.

****

Three wishes...

As Sir Arthur C. Clarke turns 90 this year, on December 16th, on a recent message he released for his birthday he says, “As I complete 90 orbits, I have no regrets and no more personal ambitions. But if I may be allowed just three wishes, they would be these:
Firstly, I would like to see some evidence of extra-terrestrial life. I have always believed that we are not alone in the universe. But we are still waiting for ET’s to call us – or give us some kind of a sign. We have no way of guessing when this might happen – I hope sooner rather than later!

Secondly, I would like to see us kick our current addiction to oil, and adopt clean energy sources. For over a decade, I’ve been monitoring various new energy experiments, but they have yet to produce commercial scale results. Climate change has now added a new sense of urgency. Our civilization depends on energy, but we can’t allow oil and coal to slowly bake our planet…

The third wish is one closer to home. I’ve been living in Sri Lanka for 50 years – and half that time, I’ve been a sad witness to the bitter conflict that divides my adopted country.
I dearly wish to see lasting peace established in Sri Lanka as soon as possible. But I’m aware that peace cannot just be wished -- it requires a great deal of hard work, courage and persistence.”


, , , , ,

Apophis: A close call…


The Earth is under constant bombardment. Each year, many fragments of debris hit our planet. Fortunately for us, most are so small that they burn up harmlessly in the atmosphere.
However, there are hundreds of larger asteroids orbiting near the Earth. Many scientists now believe that one of these hit the Earth 65 million years ago, killing the dinosaurs, along with 90% of all life on the planet. What is more, it is only a matter of time before the Earth is hit again.

Apophis – previously known by its provisional designation 2004 MN4 – is a Near-Earth asteroid that caused a brief period of concern in December 2004 because initial observations indicated a relatively large probability that it would strike the Earth in 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth or the Moon in 2029. However there remained a possibility that during the 2029 close encounter with Earth, Apophis would pass through a "gravitational keyhole", a precise region in space no more than about 400 meters across, that would set up a future impact on April 13, 2036. This possibility kept the asteroid at Level 1 on the Torino impact hazard scale until August 2006.


Additional observations of the trajectory of Apophis revealed the "keyhole" would likely be missed and on August 5, 2006, Apophis was lowered to a Level 0 on the Torino Scale – a method for categorizing the impact hazard associated with Near Earth Objects. As of October 19, 2006 the impact probability for April 13, 2036 is estimated at 1 in 45,000. 

Basic data...

Apophis belongs to a group called the "Aten asteroids", asteroids with an orbital semi-major axis less than one astronomical unit. This particular one has an orbital period about the Sun of 323 days, and its path brings it across Earth's orbit twice on each passage around the Sun.

It was discovered on June 19, 2004, by Roy A. Tucker, David J. Tholen, and Fabrizio Bernardi of the NASA from Kitt Peak National Observatory.

When first discovered, the object received the provisional designation 2004 MN4, and news and scientific articles about it referred to it by that name. When its orbit was sufficiently well calculated it received the permanent number 99942, the first numbered asteroid with Earth-impact solutions. Receiving a permanent number made it eligible for naming, and it promptly received the name "Apophis" as of July 19, 2005. Apophis is the Greek name of the Ancient Egyptian god Apep, "the Destroyer", who dwells in the eternal darkness of the Duat (underworld) and tries to destroy the Sun during its nightly passage.


Close approaches...

After the Minor Planet Center confirmed the June discovery of Apophis, the next close approach was computed to be April 13, 2029. On that date, it will become as bright as magnitude 3.3 (visible to the naked eye from rural and some darker suburban areas, visible with binoculars from most locations). It is important to note that the close approach in 2029 will substantially alter the object's orbit, making predictions uncertain without more data.

The NASA report on December 24, 2004, mentioned impact chances of "around 1 in 62", which was widely reported in the media, resulting in an update to the initial report and an upgrade to a Torino scale rating of 4. But later with observations from around world through 2006 resulted in Apophis being lowered to Torino Scale 0 on August 6, 2006. 

Since the odds of impact are known to be very low, the possible effects of an impact are largely irrelevant. However, the initial reports resulted in widespread discussion on many Internet forums, including armchair speculation about exactly where Apophis (then known only as 2004 MN4) would hit and what would happen when it did.
NASA estimated the energy that Apophis would have released if it struck Earth as the equivalent of 400 megatons of TNT. The impacts which created the Barringer Crater or caused the Tunguska event are estimated to be in the 10-20 megaton range. The 1883 eruption of Krakatoa was the equivalent of roughly 200 megatons.
The exact effects of any impact would have varied based on the asteroid's composition, and the location and angle of impact. Any impact would have been extremely detrimental to an area of thousands of square kilometres, but would have been unlikely to have long-lasting global effects, such as the initiation of an impact winter.

The astroid Apophis was a close call and also was an eye-operner for all the scientists around the world to be ready for any future hazards of astroids or comet impacts.

Thilina Heenatigala
General Secretary
Sri Lanka Astronomical Association




Event – Comet 17P/Holmes

All over the world astronomy enthusiasts have been stunned and surprised by the weirdest new object appearing in the sky these days. It's one of the brightest objects visible and if you know where to look, without a fuss it's easy to spot with your eyes alone. A small and very faint comet has surprised observers around the world by overnight becoming bright enough to see with the unaided eye. Observers worldwide had no trouble spotting Comet Holmes even through the full moonlight on the evening of October 25, 2007.

About a week ago periodic Comet 17P/Holmes brightness suddenly rocketed by nearly a million times virtually overnight. The comet erupted from a very dim magnitude 17 to about magnitude 2½. On an astronomer’s scale, smaller numbers mean brighter objects. From urban locations, a 3rd-magnitude object might be hidden by light pollution, but even under urban skies Comet Holmes would be clearly visible. Within a day its star-like nucleus had expanded into a perfectly round, bright little disk visible in binoculars and telescopes.

The first person to notice the out burst of Comet Holmes, according to Central Bureau for Astronomical Telegrams was J. A. Henriquez Santana at Tenerife, Canary Islands, October 23–24, 2007. The comet was then about 8th magnitude, but within minutes Ramon Naves and colleagues in Barcelona, Spain, caught it at magnitude 7.3. But it became easily visible to the naked eye as a bright yellow "star" in the northeast sky within Perseus. 17P/Holmes appeared as the third brightest "star" in Perseus by October 25. 



History

Comet 17P/Holmes was discovered in November 6, 1892 by Edwin Holmes, in London England, whilst doing his regular observations of the Andromeda Galaxy (M31). That time it was no brighter than magnitude 17 in mid October—that's about 25,000 times fainter than the faintest star that can normally be seen without any optical aid. In order to view an object this faint, one would need a moderately large telescope.

The comet was undergoing magnitude changes similar to the 2007 outburst. 17P/Holmes brightened to about magnitude 4 or 5 and then faded over several weeks. The first elliptical orbits were independently calculated by Heinrich Kreutz and George Mary Searle. The 1899 and 1906 appearances were observed, but the comet was lost after 1906 until recovered on July 16, 1964 by Elizabeth Roemer (US Naval Observatory) and the comet has been observed on every return since.

Comet 17P/Holmes is part of Jupiter's "family" of comets—a group in which the far end of their respective orbits (aphelia) cluster around the orbit of Jupiter and takes 6.88 years to make one circuit around the Sun.




What are Comets?

Comets are one of most interesting obejects in the univers because of its life style. Think of a comet as a big, dirty, gassy snowball. Comets are formed in the ring of rocks, dust, and ice that orbits the Sun beyond Pluto called the Kuiper Belt. They form when rocks, dust, and ice condense. As a comet grows larger, it starts to be pulled towards and around the Sun. They take many years to go around the Sun – from a few dozen years to many thousands of years. This is because they start to orbit the sun from very far away. They make long, egg-shaped orbits around the Sun instead of almost circular ones like the planets.

When comets are very far away from the Sun, they are covered in a coating of icy, black rocks and dust. As a comet approaches the Sun, however, the ice starts to melt. This creates large amounts of water and gas that break through the coating, freeing some of the dust and rocks. Sometimes this water, gas, rocks, and dust can be seen from the Earth as one or two tails streaming away from the comet. Even when only one tail can be seen, there are two, one made from the lighter gas and water, and the other from the rocks, dust, and chunks of ice. Comets themselves are usually between a few miles and several hundred miles in size, but their tails can be several million miles long.


How to observe the comet 17P/Holmes

The comets that can be seen in the sky without telescopes are unusual. You might only have the chance to see one once or twice during your life. Most comets can only be seen with a telescope. But now we have got the opportunity to fullfill a lifetime experience with the comet 17P/Holmes. Many astronomy enthusiasts and general public around the world so keen on seeing this spectacular fussy object in the sky.


These days it’s visible in the sky from around 8pm to 4am in the morning (in local time). Around 11pm it’ll be on the Meridian line (an imaginary line which connects North and South in the sky) - visually you have to look straight up and then bit towards North. It lies on the star constellation Perseus which is to the North-west of the beautiful Pleiades (M45). By this time Moon is setting in the west, so that you will get good views. At the time I’m writing this article it lies about 1.5 astronomical units away from us. With a help of a star chart you’ll be easily able to find Perseus. (Free star charts can be obtain from www.skymaps.com)

But don’t expect to see a tail as in you have seen pictures of comets in books and magazines. Because the tail is pointing nearly away from us in space — we're looking down its length — since the comet is nearly on the opposite side of Earth from the Sun. From the comet's viewpoint, the Earth and Sun are only about 15° apart, and this phase angle will stay small for many months. So we'll keep looking down the tail.


But you can see a round, sharp-edged disk with a bright core in binoculars and telescopes. For naked eye it’ll look like a yellowish star. Comet Holmes is likely to remain bright and continue to enlarge in the coming days, as it makes its way slowly westward across Perseus. The comet will stay in Perseus all the way into next March.

Since this is a life time opportunity, you might not want to miss it. I would like to hear your views of the comets if any of you get a chance to observe it and would willing to give tips and help out anyone with a good telescope or binocular who would like to do advance observation.

Though it’s very much weather permitting let’s hope for clear skies!

Thilina Heenatigala
General Secretary
Sri Lanka Astronomical Association


History changed on 4th October 1957, to be exact — a 100-tonne modified Soviet rocket blasted off from Kazakhstan carrying a small metal ball (58 cm. or 22.8 inches in diameter), weighed only 83.6 kg. or 183.9 pounds, equipped with only a couple of simple radio transmitters and took about 98 minutes to orbit the Earth on its elliptical path.- the world’s first satellite. Known as Sputnik (‘Companion’ or ‘Satellite’), the basketball-sized sphere became a sensation as it circled the planet transmitting a ‘beep beep’ signal. The world was never the same again.

That launch ushered in new political, military, technological, and scientific developments. While the Sputnik launch was a single event, it marked the start of the space age and the U.S.-U.S.S.R space race. Since then, spaceflight technologies have grown up. High-performance rocket fuels, miniaturized guidance electronics and ultra-light spacecraft materials, to name a few, make frequent and complex trips to space possible.

Half a century after Sputnik, space technology is part of our everyday lives. We rely on satellites for TV and long-distance phone calls, weather forecasting, navigation and disaster monitoring. Space observatories are studying the birth of planets, stars, galaxies and the Universe itself. Spacecraft have visited almost every major body in the Solar System. And 12 people have walked on the Moon.


Sputnik program

The Sputnik program was a series of unmanned space missions launched by the Soviet Union in late 1957 to demonstrate the practicability of artificial satellites for exploring the upper atmosphere as part of the International Geophysical Year. It included Sputnik 1, the first man-made object to orbit earth.
The Russian name "Спутник" means literally "co-traveler","traveling companion" or "satellite", and its R-7 launch vehicle was designed initially to carry nuclear warheads.
The surprise launch of Sputnik 1, coupled with the spectacular failure of the United States' first two Project Vanguard launch attempts, shocked the United States, which responded with a number of early satellite launches, including Explorer I, Project SCORE, and Courier 1B. The Sputnik crisis also led to the creation of the Advanced Research Projects Agency, DARPA and NASA, and to major increases in U.S. government spending on scientific research and education.

Early flights
Sputnik 1 was launched on October 4, 1957. The satellite was 58 cm (about 23 in) in diameter and weighed approximately 83.6 kg (about 183 lb). Each of its elliptical orbits around the Earth took about 96 minutes. Monitoring of the satellite was done by Amateur radio operators. 

Sputnik 2 was launched on November 3, 1957 and carried the first living passenger into orbit, a dog named Laika. The mission planners did not provide for the safe return of the spacecraft or its passenger, making Laika the first orbital casualty. This mission was promptly dubbed "Muttnick" by US humorists. 
The first attempt to launch Sputnik 3, on February 3, 1958, failed, but the second on May 15 succeeded, and it carried a large array of instruments for geophysical research. Its tape recorder failed, however, making it unable to measure the Van Allen radiation belts.
Sputnik 4 was launched two years later, on May 15, 1960.
Sputnik 5 was launched on August 19, 1960 with the dogs Belka and Strelka, 40 mice, 2 rats and a variety of plants on board. The spacecraft returned to earth the next day and all animals were recovered safely.
Sputnik 40 and Sputnik 41
Sputnik 40, also called Sputnik PS2, Radio Sputnik 17 and Mini-Sputnik, was a 1⁄3-scale model amateur radio satellite launched from the Mir space station on 3 November 1997 to commemorate the 40th anniversary of Sputnik 1. The spacecraft body resembled Sputnik 1 and was built by students at the Polytechnic Laboratory of Nalchik in Kabardino-Balkaria. The transmitter was built by students from Jules Reydellet College in Réunion, with technical support from AMSAT-France. Its batteries expired on 29 December 1997 and the VHF transmitter fell silent. 
Sputnik 41 was launched a year later, on 10 November 1998. It also carried a transmitter.


Next 50 years…

If the last 50 years mark the beginning of a new era for the human race, who knows what will be achieved in the next half century? This October will mark the 50th anniversary of Sputnik 1, the first artificial satellite of Earth. Fifty years from now, scientists, explorers – even tourists, I expect – will be on Mars, will be cruising through the asteroid belt, and will be beginning the exploration of Jupiter and the outer planets. Perhaps you will be one of the first people to spend a holiday on the Moon or set foot on Mars.

Thilina Heenatigala
General Secretary
Sri Lanka Astronomical Association

Instructor
Royal College Astronomical Society

, ,

Once in a Blue Moon

When you hear someone says "Once in aBlue Moon…" you know what they mean: Rare, Seldom, or maybe even absurd. After all, when was the last time you saw the moon turn blue?
But what exactly is a Blue Moon? Is there a scientific meaning behind this phrase or does the moon really turns blue?

In astronomical terms, a 'blue moon' really doesn't have anything to do with color. Instead, it is the term used to denote the second full moon that occurs within a given calendar month. Because it takes the moon about 29 days to circle the Earth once in its orbit, it is possible that two full moons can occur within the same calendar month. On average, this takes place once every two and a half years. A second blue moon will appear this May, with the moon displaying its full-phase on the 1st and the 31st of May, 31st would be the “Blue Moon.”

Although a 'blue moon' doesn't really look blue, there have been times when the moon does seem to have a blue color. This can be caused by dust particles in the atmosphere, which scatter light. The effects of this dust on the light coming from the moon can cause it to appear bluish in color. Fine dust particles are ejected into the Earth's upper atmosphere after large volcanic eruptions, for example. The eruption of the Krakatoa volcano in 1883 gave us one such 'blue moon'. For about 24 months after this volcano exploded, the dust it spewed into the upper atmosphere caused the moon to appear green and blue when viewed from around the world. Even in a case like forest fire or due to large amount of smoke moon would look bluish.

There is little scientific significance to either an astronomical blue moon or a bluish-looking moon. But astronomers are interested in how the moon reflects different colors. The moon generates no light of its own, but reflects light from the Sun. By studying how the moon reflects this light, scientists can explore the chemical composition of the lunar surface.

Other Meanings

According to old folklore, some people say, the second full Moon in a calendar month is called a "Blue Moon." They go on to explain that this is the origin of the expression "once in a blue Moon." But the term "blue Moon" has been around a long time, well over 400 years, but its calendrical meaning has become widespread only in the last 20 years. 

Philip Hiscock, an author and archivist of Folklore & Language Archive, Memorial University of Newfoundland, camp up with seven meanings to the phrase “Blue Moon”.

Seven meanings of 'Blue Moon':

1. as an ABSURDITY. 'He would argue that the moon is blue!', as if to say, he would argue that black is white! Such expressions can be found in the literature of the 16th century.

2. NEVER. "I wouldn't be seen with him even if the moon turned blue." This use was apparently common in the 1900's.  

3. ACTUALLY IS BLUE. Seen against a blue sky in daytime or twilight, our eyes may see the moon as a bluish tint. Smoke or dust in the air can emphasize the blue or other color.

4. RARE. An actual blue moon color is fairly uncommon, so the term took on the meaning of rarity or, 'I only do this once in a blue moon'.

5. SADNESS, LONELINESS. Well, there is only one up there! It can and does console us when we are alone and blue.

6. There is a drink, made from Blue Curacao, called BLUE MOON

7. SECOND FULL MOON IN A CALENDAR MONTH. Because 11 of the twelve months have more days than the lunar cycle of 29 1/2 days, it is easily possible for a month to have two full moons. And this is the meaning we use nowadays.

Then according to Sri Lankan calendrical full moons, we call as “Poya days”. While for the 2nd full moon of the month we use the name “Adhi Poya”. Which I beilive must have a history than the western definition of the 2nd full moon of the month. If anyone has an earlier reference in published literature to the “Adhi Poya”, please write to me.

Since the next Blue Moon occurs in December of 2009. Don’t miss the opportunity to view the Blue Moon on 31st of May. The Moon will be visible from 6pm on wards and the Planet Jupiter will lies closer to moon on the date which will make it a fascinating site.



Thilina Heenatigala
Secretary
Astronomical Association of Lanka

Dedicated to Keshya Kumaranayagam.

,

Total Lunar Eclipse of March 03

A unique total lunar eclipse, that it is partly visible from every continent around the world.

Next Saturday the March 3rd Poya day Night (Sunday Early Morning), there will be a Total Eclipse of the Moon which is visible to us. The total phase lasts 73 minutes. The Penumbral stage which begins at 1:48AM there is only a dimming of the brightness of the Moon which is not easy to notice. But after 3:00AM the Moon will start moving into the shadow cast of the Earth by the Sun. From 4:14AM to 5:27AM the Moon is totally eclipsed illuminated only by Earth light. Though depending on Atmospheric conditions it may be seen glowing red in color. The Partial Eclipse ends after sunrise around 6:15 AM on the East coast and 6:22 AM in Colombo and moonset at 6:29 AM


Lunar Eclipses

An eclipse of the Moon (or lunar eclipse) can only occur at Full Moon, and only if the Moon passes through some portion of the Earth's shadow. The shadow is actually composed of two cone-shaped components, one nested inside the other. The outer or penumbral shadow is a zone where the Earth blocks part but not all of the Sun's rays from reaching the Moon. In contrast, the inner or umbra shadow is a region where the Earth blocks all direct sunlight from reaching the Moon. 

 

Geometry of the Sun, Earth and Moon during a Lunar Eclipse. 
Earth's two shadows are the penumbra and the umbra. 



Three basic types of lunar eclipses:

1. Penumbral Lunar Eclipse - The Moon passes through Earth's penumbral shadow. 

2. Partial Lunar Eclipse - A portion of the Moon passes through Earth's umbra shadow. 

3. Total Lunar Eclipse - The entire Moon passes through Earth's umbra shadow. 

Moon's orbit around Earth is actually tipped about 5 degrees to Earth's orbit around the Sun, means that the Moon spends most of the time either above or below the plane of Earth's orbit. And the plane of Earth's orbit around the Sun is important because Earth's shadows lie exactly in the same plane. During Full Moon, our natural satellite usually passes above or below Earth's shadows and misses them entirely and no eclipse takes place. But two to four times each year, the Moon passes through some portion of the Earth's penumbral or umbra shadows and one of the above three types of eclipses occurs. 

During a total lunar eclipse, the Earth blocks the Sun's light from reaching the Moon. While the Moon remains completely within Earth's umbra shadow, indirect sunlight still manages to reach and illuminate it. However, this sunlight must first pass deep through the Earth's atmosphere which filters out most of the blue colored light. The remaining light is a deep red or orange in color and is much dimmer than pure white sunlight. Earth's atmosphere also bends or refracts some of this light so that a small fraction of it can reach and illuminate the Moon. 

Observing Lunar Eclipses

Not as solar eclipses, lunar eclipses are completely safe and easy to watch. You don't need any kind of protective filters. And most of all you don’t need a telescope. You can watch the lunar eclipse with nothing more than your own two eyes. If you have a pair of binoculars, they will help magnify the view and will make the red coloration brighter and easier to see. 
Of course, an eclipse of the Moon also presents a tempting target to photograph. So if you have any digital or SLR camera, try doing some photography. But remember to dress warmly and take time to enjoy the spectacle! 

Thilina Heenatigala  
General Secretary 
Astronomical Association of Lanka

Popular Posts

Note from the writer

This blog contains some of the articles I have written over the years. It's not the complete list as my writing have become more frequent and not really finding time to update the blog.

Hope to update it properly one day, enjoy the pieces I have already uploaded.

Cheers!
Thilina Heenatigala

Followers

Subscribe Via Email