The most eagerly awaited event of the astronomical calendar this year will pass us here on Earth on the 6th June. There are two Transits of Venus eight years apart but as this happens at intervals of more than 100 years we will have to wait until 2117 before we see it again.
The brilliant beacon of Venus signals the promise of the day to come and as the Evening Star, trails the Sun into the fall of night. Venus the God of love and beauty and the name of the planet shrouded in what for centuries was believed to be watery clouds from which the light reflected from the Sun creates the famous glowing beacon apparently covering a romanticised tropical paradise. The truth is rather different. Venus our closest planet at just 41,000,000 kilometres is a hell with toxic pressure nearly 100 times that on Earth combined with a surface temperature of 475 degrees centigrade. As for that luminous glowing envelope of cloud, it has proved to be an evil cocktail of carbon dioxide with a splash of sulphuric acid creating a ferocious green house effect.
For the astronomers Venus has always been of the greatest importance. As early as 1716 Edmond Halley [1656-1742], later to become Astronomer Royal, accurately predicted not only the next appearance of the Comet named after him but also the Transits of Venus of 1761 and 1769. When all these events occurred it became a defining moment in the world of science as Halley’s calculations were based on the mathematics published by Isaac Newton in “The Principia” of 1687. Graphic proof indeed of the Newtonian Revolution. Halley believed, correctly, that the parameters gained from the Transits would enable the determination of the distance between the Earth and the Sun which in turn could lead to the estimation of the size of the Solar system – the Holy Grail of Astronomy.
This year the very best position to witness the Transit of Venus will be in Hawai’i where the Sun will be directly overhead. Here in Great Britain the sighting will not be as extensive as it was in 2004 but it is still an exciting prospect not to be missed. Although the event starts at 11:10am BST on the 5th June , in G.B. it will not be visible until sunrise the following morning near the end of the Transit which lasts nearly 6 hours. At this time of year sunrise is early. In Edinburgh it will be at 3:30am BST, in London a little later at 3:45am and at Penzance later still at 4:15am.
Venus will appear as a black disc slowly traversing the burning hot face of the Sun always assuming that it is not obscured by cloud. Venus in Transit belies the regular morning and evening dazzling globe – Venus the Queen of Diamonds.
WARNING – Never look towards the Sun without the Correct eye protection. It is essential to seek professional advice.