New Delhi: May 04: A transit of Mercury over the disc of the Sun will take place in the afternoon of May 9, 2016 (19 Vaishakha, 1938 Saka Era).
This transit phenomenon will be visible from India. This phenomenon takes place when the planet Mercury will be seen as a small black dot travelling from one limb of the solar disc to the other. From the Earth this phenomenon is seen when the Mercury passes between the Sun and the Earth.
This happens only when the Sun, the planet Mercury and the Earth are lined up in one plane. The Mercury appears as a dot on the solar disc because its angular size is very small compared to that of the Sun as seen from the Earth.
The transit begins with Contact-I, the instant when the disc of the planet Mercury is externally tangent with the Sun (Ingress exterior) followed by Contact-II,when the Mercury is internally tangent with the Sun (Ingress interior). The Mercury will be seen as a black spot, traveling several hours over the face of the disc, will reach the opposite limb of the Sun at Contact-III, when the disc of the planet Mercury is internally tangent with the Sun (Egress interior). Finally, the transit ends at Contact-IV when the disc of the planet Mercury is externally tangent with the Sun (Egress exterior).
The phenomenon is a relatively rare one which occurs 13 or 14 times in a century. It occurs in the month of May and November. The interval between one November transit and next November transit may be 7, 13 or 33 years whereas the interval between one May transit and the next May transit may be 13 or 33 years.
The transit of Mercury will be visible from most of Asia (except south eastern parts and Japan), Europe, Africa, Greenland, South America, North America, Arctic, North Atlantic Ocean and most of the Pacific Ocean. The entire transit, from beginning to end, will be visible from eastern North America, northern South America, the Arctic, Greenland, extreme northwestern Africa, western Europe, and the North Atlantic Ocean.
In India, the beginning of the event comprising of Ingress exterior (Contact-I) and Ingress interior (Contact-II) will be visible from all places. The duration of the entire transit event will be about 7 hour and 30 minutes. The observer in India will not see the ending of the event as the same will be in progress after sunset. Depending upon the sunset time of different places in India, the observer located in the extreme east of the country will see the event about 1 hour from the beginning and the observer located in the extreme west of the country will see the event about 2 hours and 45 minutes from the beginning.
In Delhi, the event can be seen for a duration of about 2 hours 20 minutes as it will start at 16h 41m IST and sunset will take place at 19h 01m IST. Similarly, in Kolkata the event will start at 16h 41m IST and it can be seen for a duration of about 1 hour 26 minutes, in Mumbai the event will start at 16h 41m IST and it can be seen for a duration of about 2 hours 24 minutes, in Chennai the event will start at 16h 41m IST and it can be seen for a duration of about 1 hour 45 minutes.