Post date: May 24, 2012 2:23:14 PM
Next month astronomers across the world will be hoping to get a clear view of the Transit of Venus for the last time in their lives. On June 5 and 6, Venus will pass directly between Earth and the Sun, visible as a small black dot gliding slowly across Sun's face. The Transits occur in a pattern that repeats every 243 years, meaning the next Transit won't appear for another 105 years. Jim Drury has more.
REUTERS / NASA / NOAA / NATIONAL MARITIME MUSEUM - Venus dwarfed by the Sun as it passes across its face in 2004..an event witnessed only six times since 1639.
On June 5 and 6 the Transit of Venus occurs again, to the delight of astronomers worldwide.It's the last chance they'll get to see the celestial event.
The Transit occurs in two stages eight years apart. There won't be another for more than a century.
Dr Marek Kukula, public astronomer at London's Royal Observatory in Greenwich says sky-watchers are in for a treat.
DR MAREK KUKULA, PUBLIC ASTRONOMER FOR LONDON'S ROYAL OBSERVATORY, SAYING:
"This animation shows you how the Transit of Venus occurs and what people here on Earth can expect to see. So Venus is moving between the Earth and the Sun and when it does that people on the surface of the Earth will see Venus as a tiny black dot silouhetted against the Sun. So they'll get a view something like this with this tiny black dot which is the planet Venus moving across the face of the Sun and it takes Venus several hours to cross from one side to the other."
Getting a decent view of the transit in reality will depends on your location.
DR MAREK KUKULA, PUBLIC ASTRONOMER FOR LONDON'S ROYAL OBSERVATORY, SAYING:
"The best places are in Asia and around the Pacific where you should be able to see all of the Transit. People in North America should see the beginning of the Transit, just before the Sun sets, and people in Europe will get a chance to see the end of the Transit just as the Sun is rising on June 6. It's only people in western Africa and south America who won't be able to see any of it because it happens at night when the Sun is on the other side of the Earth."
The transits of the 18th and 19th Century were crucial to understanding the size of the solar system.
Astronomer Edmond Halley, for whom a comet was famously named, was the first to correctly forecast when the transits would occur.
But knowing he'd be dead when the Transit appeared in June 1761, Halley encouraged his successors to collaborate.
It heralded the beginning of the era of international scientific collaboration, according to Royal Observatory curator Dr Rebekah Higgitt.
DR REBEKAH HIGGITT, CURATOR OF THE HISTORY OF SCIENCE AND TECHNOLOGY AT THE ROYAL OBSERVATORY, SAYING:
"Very famously you get some maritime expeditions being sent across to other parts of the world, as far apart as they could, and very famously for Britain in 1769 that was the voyage led by Captain James Cook who went to Tahiti to observe the Transit in 1769.....One of the instruments behind me is something that was built for 1874, a photoheliograph telescope and they made five of those by the same makers so they could all be essentially exactly the same. You're sending people to other sides of the world, but you want them to be able to produce results which can be compared with each other."
21st century technology will open the next Transit to a wider audience than ever before although for many, it'll be far more than an entertaining diversion.
DR REBEKAH HIGGITT, CURATOR OF THE HISTORY OF SCIENCE AND TECHNOLOGY AT THE ROYAL OBSERVATORY, SAYING:
"There are also scientific rational for observing as well. One of them is in relation to the 'black drop effect', which was first observed in the 18th Century and is still not entirely understood as to what's causing that. Whether it's to do with the Sun's atmosphere, the Earth's atmosphere, an optical illusion and so on, so there's still a number of questions there."
In 2004 the Royal Observatory saw hundreds of visitors watching the Transit, through telescopes or special eclipse glasses. Staring at the Sun with unprotected eyes can cause serious damage.
The Pyramids in Cairo served as another backdrop for a host of amateur astronomers, all of whom are polishing their glasses and preparing their telescopes for the second stage of this once-in-a-lifetime event.
Jim Drury, Reuters