rare celestial event - transit of venus on june 8 2004

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THE TRANSIT OF VENUS

 

ON JUNE 8, people in many parts of the world, including most of Asia, Africa and Europe, will witness a rare celestial event — the `transit of Venus' that occurs as the planet passes directly between the Earth and the Sun. Venus will appear as a black blob traversing the bright face of the Sun for six hours. As the last transit of the planet occurred 122 years ago, it does appear that no one alive has witnessed such an event. Those who miss next week's transit will have another chance on June 6, 2012. After that the phenomenon will recur in 2117. The transit of Venus has been closely associated with the development of astronomy. It has inspired nations to mount scientific expeditions to the far corners of the globe to observe these events. Predicting the transits required a sound understanding of the inner planets' orbits, which became possible only in the early 17th Century when Johannes Kepler established the laws of planetary motion. He

relied on the Copernican system of the planets orbiting the Sun rather than the geocentric model where the Moon, the Sun, Mercury, Venus, Mars, Jupiter and Saturn were thought to circle the Earth. His publication of the Rudolphine Tables made computation of planetary positions, past and future, possible. The accuracy of the tables was a telling argument for the correctness of Kepler's laws and of heliocentric astronomy. Using the tables, the great man predicted a transit of Mercury in November 1631 and a transit of Venus a month later; he did not live to see either. It was the English astronomer, Edmund Halley, who first realised that the Earth-Sun distance could be computed more accurately if a transit of Venus were observed from widely separated places. At the time, relative distances were known, such as that Jupiter was five times farther from the Sun than the Earth was from the Sun. If the Earth-Sun distance was accurately estimated, then these relative numbers could be converted into absolute values and the size of the solar system would be known. Halley published his ideas in the Philosophical Transactions of the Royal Society. Soon, sending people to the far corners of the world to observe the transits became a matter of national scientific prestige. Britain, for instance, sent a team under Captain James Cook (then an unknown lieutenant), which made its observations of the 1769 transit of Venus from the Pacific island of Tahiti. In the end, observations of the transits of Venus did not yield an accurate figure for

the Earth-Sun distance as clocks of the time were not accurate enough and it was difficult to establish precisely when Venus, visible as a black drop rather than as a circle, appeared to have entered the disk of the Sun. Eventually the Earth-Sun distance, which is called the Astronomical Unit, was estimated by bouncing radar signals off Venus in the early 1960s. The transits of Venus next week and in 2012 offer a major challenge: developing new techniques for the detection and characterisation of extra-solar planets (those revolving around stars other than the Sun). All the extra-solar planets detected thus far are too large to support life forms similar to those on Earth. The Hubble Space Telescope observed 50,000 stars in June 2003, looking for signs of planetary transits. A drop of 0.01 per cent in a star's luminosity during a planetary transit could suggest an Earth-sized planet; the results from the Hubble observations are expected later this year. Once more, scientist and layperson alike can share the excitement that a transit of Venus offers. source the hindu http://www.hindu.com/2004/06/05/stories/2004060500691000.htm with love ajoy Mata-Amritandamayi/Do You ?Get your free @.hk address at Mail.