Transit of Venus vying with the Monsoons - Part 1

We have had two chances in our lifetimes to see Planet Venus traipsing across the disc of the Sun. On 8 June 2004 came the first of the pair of transits of Venus and the second, on June 6, 2012, will be the last in this century. The next time people on earth will witness the rare spectacle of Venus moving across the disc of the Sun will be in December 2117. So this event has caused a flurry among astronomers professional and amateur.

If Venus orbits the Sun in the same plane as the orbit of the Earth we would see such transits often. But since its orbit is inclined to the Earth by about 3.4 degrees, when Venus passes between the Sun and Earth every 1.6 years, it is usually a little below or a little above the line joining Earth and Sun. We only see transits on those rare occasions when the three objects are in an inferior conjunction, or a straight line with the Sun and Venus on the same side of the Earth. When Venus passes between the Sun and the Earth near the nodes a transit occurs. The points where the orbit of Venus crosses the Ecliptic are called the Nodes.

Transits of Venus take place at regular intervals, four times in 243 years, and in pairs separated by eight years. There is such a pair, then there is a span of 105.5 years without any transit then another pair separated by eight years and then a gap of 121.5 years.

The first recorded viewing of the transit was by Jeremiah Horrocks in 1639, about thirty years after the discovery of the telescope.  Since then transits have been observed in 1761, 1769, 1874, 1882 and 2004.

In order to promote the idea of viewing the celestial event, the Tamilnadu Science and Technology Centre supported by Vigyan Prasar has held awareness camps all over the country. Workshops for teachers were held in April and May each lasting three days for about 50 people selected from schools close to that area. The last of these camps was held at Anna Science Centre – Planetarium in Tiruchirapalli between 25 and 27 May 2012,  for Post-graduate teachers; Elementary education officers and Science communicators from Kerala, Puducherry and parts of southern Tamilnadu. About 65 people participated in the workshop.