Giving thousands of sky gazers a rare visual treat, the planet Venus on Tuesday started its transit across the Sun even as as experts warned against watching the event through the naked eye.
"Star gazers have gathered here to watch the once in a lifetime event. Venus appears as a tiny black dot passing across the face of the Sun," Director, Nehru Planetarium, Dr N Rathnasree, said.
The brightest planet after about 122 years started crossing the disc of the Sun at 1043 IST and will take about six hours to cross it, she said.
Rathnasree, however, warned against looking at the Sun through the naked eye as it may lead to eye problems.
"Looking directly at the Sun could lead to vision problems," she said, adding the safest method is to see it through a projection," she said.
The event, similar to a solar eclipse, is visible from all over India. Since the Venus does not cover the face of the Sun, it appears as a tiny dot moving from the Sun's south eastern edge to south western, president of an amateur astronomers NGO, SPACE', Amitabh Pandey, said.
As the planet crosses the Sun, it would appear to be nearest to the Sun on the 'Ubaidullahgan' mountain near Panchmarhi in Madhya Pradesh, Rathnasree said.
The event has a historical importance, Pandey said, adding "such transits in 1761 and 1769 were used by the international scientists to measure the distance from the earth to the Sun."
Venus transits are very rare. "No one alive so far has seen the transit of Venus. The last time this happened was in 1882 and in 1874," Rathnasree said.
Thus, it is almost a lifetime opportunity as next Venus transit would occur in 2012 and after that the event is slated only in the 22nd century, she added.
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