Rare transit of Venus on Wednesday

With the sunrise on Wednesday, Sri Lankans will have a chance to witness one of the rarest celestial phenomena known as 'Venus Transit'. Millions around the world will witness this rare astronomical phenomenon.

Such an event occurs when the planet Venus passes almost exactly between the Earth and the Sun in a kind of eclipse. During the transit, Venus appears as a small black disc moving across the sun usually taking nearly seven hours.

Transits of Venus occur at regular intervals that repeat over a 243-year period. Intervals between successive transits are eight years, 105.5 years, eight years, and 120.5 years.

The last transit in the current cycle was in June 2004, but before that the last transit was in December 1874 and December 1882.

The next transit will be in December 2117 and December 2125.

The passage of Venus in front of the Sun on June 6 will be visible in its entirety in the Arctic areas as well as in eastern parts of Asia and Australia.

However, Sri Lankans would see only the latter part of it for the transit begins around 3.39 a.m. Sri Lanka standard time, before the sunrise.

The Venus transit will be visible to Sri Lanka from about 6.00 a.m. on Wednesday with the sunrise, greatest of transit at 7.03 a.m. and the transit ends at 10.22 am.Observing the transit will not require a telescope. However, extreme precaution must be taken when observing the event or permanent eye damage and/or blindness will occur.

Therefore the Venus transit should not to be observed with the naked eye.

The same protection used during a solar eclipse should be used, said Prof. Chandana Jayarante, Professor in Physics, University of Colombo and Consultant to the Space Science Division Arthur C. Clarke Institute for Modern Technologies.

A projection technique, solar filter or no. 14 welder's glass are good choices. However sun-glasses or tinted glassed are not.