The phenomenon occurs when venus passes between the sun and earth and the planet gets aligned with the former.
This is an extremely rare event which occurs in pairs, eight years apart, about once a century. The next pair of transit of Venus will occur after a century on December 11, 2117 and on December 8, 2125.
"Venus Transit is a rare astronomical event where Venus passes directly between the earth and the sun. The planet appears as a black spot gliding across the sun's fiery face," Nehru Planetarium Director N Rathnasree said.
The next transit of Venus will occur in 2117, making it once in a lifetime opportunity, Science Popularisation Association of Communicators and Educators (SPACE) Director C B Devgun said.
However, only the beginning phase of the event that comprises Ingress exterior, the point of the planet's first contact with the sun's disk will be visible from India.
The Ingress interior, when Venus is fully inside the solar disc, will not be visible from any part of the country.
People in eastern India can see the first part of the event after sunrise for a duration of about 5 hours 30 minutes, while those in western side will see it for about 4 hours 30 minutes.
The entire transit event will be visible from north western North America, the western Pacific, northern Asia, Japan, Korea, eastern China, Philippines, eastern Australia and New Zealand.
The last transit of Venus occurred on June 8, 2004 when the entire event was visible from all parts of India.
