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| Sunday, 6 June 2004 |
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| News Business Features Editorial
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Venus in transit: A celestial journey Pray for clear weather on June 8. For, on this day, a very rare
astronomical phenomenon, not witnessed by human eyes in 122 The last transit happened on December 6, 1882, and the next will occur in 8 years; it will be visible from the Americas. The 'transit' according to Dr. Chandana Jayaratne, principal research scientist on space applications at the Arthur C. Clarke Institute of Modern Technology, is among the rarest of astronomical events.
Transits of Venus occurs in pairs, eight years apart. A recurring pattern of either 105.5 or 121.5 years between the last transit of one pair and the first transit of the next pair always exists. The circumstances of Venus transits repeat themselves with great exactness after a period of 243 years. A pair of transits may come over a time span of just eight years, but following the second transit, the next will not occur for more than a century. The four transits of Venus which occurred in the 18th and 19th centuries rank among the most eagerly awaited astronomical observations. The last transit of Venus took place on 6 December 1882. The last one that could have been seen in its entirety from the UK, as on this occasion, was in 1283 and the next will not be until 2247! The transit of 6 June 2012 will not be visible from Sri Lanka and can be seen from only the Pacific Ocean and east coasts of Siberia, Japan and Australia. The first transit of Venus to be observed was on 24 November 1639 (Julian Calendar). Transits also occurred in 1761, 1769 and 1874. ###### The planetary equivalent to hell At first glance, if Earth had a twin, it would be Venus. The two planets are similar in size, mass and composition, and both reside in the inner part of the Solar System. Indeed, Venus comes closer to Earth than any of the other planets. Before the advent of the Space Age, astronomers could only speculate over the nature of its hidden surface. Some thought that Venus might be a tropical paradise, covered in forests or oceans. Others believed that it was a totally barren, arid desert. After investigations by numerous American and Russian spacecraft, we now know that Earth's planetary neighbour is the most hellish, hostile world imaginable. Any astronaut unlucky enough to land there would be simultaneously crushed, roasted, choked and dissolved. Unlike Earth, Venus has no ocean, no satellites and no intrinsic magnetic field. It is covered by thick, yellowish clouds - made of sulphur and droplets of sulphuric acid - that act like a blanket to trap surface heat. The upper cloud layers move faster than hurricane-force winds on Earth, sweeping all the way around the planet in just four days. These clouds also reflect most of the incoming sunlight, helping Venus to outshine everything in the night sky (apart from the Moon). At the present time, Venus dominates the western sky after sunset. ###### HOW TO VIEW In his 1885 book, "The Story of Astronomy" Professor Sir Robert Stawell Ball described his own feelings on watching the transit 3 years earlier: "... To have seen even a part of a transit of Venus is an event to remember for a lifetime, and we felt more delight than can be easily expressed... Before the phenomenon had ceased, I spared a few minutes from the somewhat mechanical work at the micrometer to take a view of the transit in the more picturesque form which the large field of the finder presents. The sun was already beginning to put on the ruddy hues of sunset, and there, far in on its face, was the sharp, round, black disk of Venus. It was then easy to sympathise with the supreme joy of Horrocks, when, in 1639, he for the first time witnessed this spectacle. The intrinsic interest of the phenomenon, its rarity, the fulfilment of the prediction, the noble problem which the transit of Venus helps us to solve, are all present to our thoughts when we look at this pleasing picture, a repetition of which will not occur again until the flowers are blooming in the June of A.D. 2004." Venus is large enough to be just visible to someone with normal eyesight without the help of binoculars or a telescope. Its diameter will appear about 1/32 the diameter of the Sun. However, NO ONE SHOULD EVER LOOK DIRECTLY AT THE SUN, WITH OR WITHOUT A TELESCOPE OR BINOCULARS WITHOUT USING A SAFE SOLAR FILTER. TO DO SO IS VERY DANGEROUS AND IS LIKELY TO RESULT IN PERMANENT BLINDNESS. For safe viewing of the transit, much the same rules apply as those for observing an eclipse of the Sun. Eclipse viewers can be used (as long as they are undamaged), and observing is limited to a few minutes at a time. (Note that they must NOT be used with binoculars or a telescope.) For an enlarged view, an image of the Sun can be projected onto a screen by a small telescope. Pinhole projection, however, will not produce a sharp enough image to show Venus clearly. According to Dr. Chandana Jayaratne, one could also try with looking at the sun's reflection on a water basin kept on the floor or projection of the sun's image on to a white wall inside the house using a mirror and a piece of paper with a small circular hole. Or, look at the patch of light created by a hole in the roof and falling onto a white paper kept on the floor. Use of smoked glass or X-ray films to watch the sun is not recommended as they may transmit infrared radiation harmful to the eye. ###### Activities at the Arthur C. Clarke Institute Sri Lankan scientists will join the world community in measuring this celebrity event using a CCD camera connected to the biggest telescope in Sri Lanka. In case of cloudy skies in Colombo, similar arrangements are made at Katharagama and Kalpitiya, says Dr. Chandana Jayaratne. Pictures taken every 15 minutes can be seen on website accimt.lk. Successful observers can send in their pictures, drawings or images to Applications Division, ACCIMT, Katubedde. |
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years, will
takes place in the Sri Lanka skies when the planet Venus lines up between
Earth and the Sun. Seen as a small black disk against the bright Sun,
Venus will take about 6 hours to complete its crossing of the Sun's face -
known as a 'transit'. The epic journey will begin at around 11.14 a.m. and
last till 5.23 p.m. and will be visible in some form across approximately
three-quarters of the Plant, including all of Asia, parts of Europe and
Africa.
Astronomers warn observers not to look directly at the Sun, or through
a telescope without a proper filter, as it can severely damage the eyes.
"Retinal damage can occur in just a few seconds when looking at the
sun with the naked eye, and in a fraction of a second with binoculars or a
telescope," says Dr. Jayaratne.
